Navigating email errors can be complex, given the myriad factors that can interfere with successful delivery. This guide elucidates common issues encountered using email services such as Mailgun and Gsuite. From domain verification to request limits, this resource offers insights into prevalent errors, their causes, and potential solutions to facilitate smoother digital communications.
Please Note:
For more information about why your email was unsuccessful, please click the ⚠️(red triangle) icon to view more details:Error list:
The domain is not allowed to send:
The domain is unverified and requires DNS configuration. Log in to your control panel to view the required DNS records.
Log in to Mailgun - https://login.mailgun.com/login/
1. Expand Sending tab
2. Click the last menu item, Domain Settings
3. Make sure you select the correct domain/subdomain for the location on top
4. Click DNS records on the top middle
5. Click Verify DNS settings and see if all 5 DNS records have a green checkmark?
Sometimes it might show if they have all green checkmarks but it might not be the case, you will need to click the Verify DNS Settings button again to refresh the record:
The domain is not allowed to send: Account Terminated.
The agency must contact Mailgun support to see why it got terminated.
Too old
It is one of Mailgun's internal errors that you can clear in the Agency settings. But to find out why you are getting that error, you will need to contact Mailgun support to check further.
Mailgun Send verification error.
If the sender's address is missing or illegible, it may never reach its destination, and even if it does, the recipient won't be able to respond. Similarly, a sender address verification error can occur in email communication if the recipient server fails to locate the sending domain's necessary MX records (Mail Exchanger records).
Here's how the problem usually manifests itself:
- 550 Verification failed for <bounce+c72392.3559d@yoursendingdomain.com>\nUnrouteable address\nSender verify failed
- The domain of the sender address bounce+c72392.3559d@yoursendingdomain.com does not exist
- Sender address rejected: User unknown in virtual mailbox table
- Could not resolve sender domain
- Your domain has no DNS/MX entries
- Requested action not taken: mailbox unavailable invalid DNS MX or A/AAAA resource record.
Here are some steps you can take to fix this issue based on your current Mailgun sending domain:
If you're using a subdomain:
Although not required, we highly recommend pointing your MX records for the domain to Mailgun. This helps prevent Sender Verification Errors.
Set the MX records for the subdomain to Mailgun values to fix the error. These are:
- Value: mxa.mailgun.org, Priority: 10
- Value: mxb.mailgun.org, Priority: 10
Wait 24-48 hours for the records to propagate fully, and the error should disappear.
If you still see the error, try adjusting the domain in the From field of the message to match the sending domain.
If you're using a root domain:
If your root domain already has your Email Service Provider's (ESP's) MX records in place, the best solution is to add a subdomain for your Mailgun sending. The error should be resolved once you've added the subdomain and configured Mailgun's MX records.
Please Note:
If your root domain doesn't have or needs MX records pointing to a hosted mailbox provider, you can add the root domain to your Mailgun account, verify the required TXT AND MX records, and send through the root domain.
Remember: Only point your MX records for a domain to one source to avoid email misdirection or loss.
3. Alternate Approaches:
If the error persists after trying the above steps, consider these alternatives:
- Turn off sender address verification (on the server side with your email provider).
- Create a "catch-all" within the configuration of your email provider. This ensures that Sender Address Verification will pass when the recipient server checks the sender information for incoming emails.
Understanding and troubleshooting these kinds of issues can be technical, but following these steps should help you resolve sender verification errors.
Too many requests
The error means that too many email requests were sent simultaneously. Please get in touch with Mailgun support to check for an email limit with the Mailgun account.
You can clear the error in the agency settings -> Email services tab.
Temporary System Problem when using Google Workspace
“code”:“EENVELOPE”,“response”:“421 4.3.0 Temporary System Problem. Try again later (10). o11-20020a056e02092b00b0031559b0cb61sm1590122ilt.8 - gsmtp”,“responseCode”:421,“command”:“DATA
If you send emails in bulk and receive the error above, this might happen when using Gmail SMTP; please inform the user to use LC Email or send in batches with low volume.
Error Libraries for Various SMTPs
Mailgun:
| Code | Error Message | Meaning | Solution | Glossary |
|---|---|---|---|---|
| 400 | from parameter is missing | The sender's email address is not provided | Include the sender's email in the 'from' parameter | 'from' parameter: Sender's email address |
| 400 | to parameter is missing | The receiver's email address is not provided | Include the receiver's email in the 'to' parameter | 'to' parameter: Receiver's email address |
| 400 | message parameter is missing | The email body is not provided | Include the email body in the 'message' parameter | 'message' parameter: Email body |
| 400 | ‘message’ parameter is not a file | The 'message' parameter is expected to be a file but isn't | Provide the message as a file | 'message' parameter: Email body, in this case expected as a file |
| 400 | Need at least one of ‘text’ or ‘html’ parameters specified | Neither plain text nor HTML versions of the email are provided | Include at least one of the 'text' or 'html' parameters | 'text'/'html' parameters: Plain text/HTML versions of the email |
| 400 | Only one parameters ‘html’ or ‘template’ is allowed | Both 'html' and 'template' parameters are provided, but only one is allowed | Provide either the 'html' or 'template' parameter, not both | 'html'/'template' parameters: HTML version of the email / Template for the email |
| 400 | Send options (parameters starting with o:, h:, or v:) are limited to 16 kB total | The send options provided exceed the 16 kB limit | Reduce the size of send options to less than 16 kB | 'o:', 'h:', 'v:' parameters: Send options for the email |
| 400 | Too many recipients; max is 1000 | The email is addressed to more than 1000 recipients | Limit the number of recipients to 1000 or less | Recipients: The individuals or groups receiving the email |
| 400 | Header name must be pure ASCII: <header-name> | The header name contains non-ASCII characters | Use only ASCII characters in the header name | ASCII: American Standard Code for Information Interchange, a character encoding standard |
| 400 | <invalid-date> is not an RFC-2822 compliant date | The provided date is not compliant with RFC-2822 | Ensure the date is formatted according to RFC-2822 standards | RFC-2822: Internet Message Format specification |
| 400 | to parameter is not a valid address. please check documentation | The receiver's email address is invalid | Check and correct the format of the receiver's email address | 'to' parameter: Receiver's email address |
| 400 | Invalid request content type. Expecting ‘multipart/form-data’ but got ‘application/x-www-form-urlencoded’ | The content type of the request is not what is expected | Change the request content type to 'multipart/form-data' | 'multipart/form-data': A type of HTTP request commonly used for file uploads |
| 400 | malformed multipart/form-data request | The 'multipart/form-data' request is formatted incorrectly | Correct the format of the 'multipart/form-data' request | 'multipart/form-data': A type of HTTP request commonly used for file uploads |
| 400 | unable to parse request: invalid URL escape | The URL in the request contains invalid escape characters | Correct the escape characters in the URL | URL escape characters: Characters used in a URL to represent certain other characters |
| 400 | unable to parse request: unexpected EOF | The request ends unexpectedly | Check the request for missing information or incorrect formatting | EOF: End of File, in this case referring to the end of the request |
| 400 | <time> invalid 24 hour time(value of ‘o:time-zone-localize’) | The time provided is not in a valid 24-hour format | Ensure the time is in a valid 24-hour format | 'o:time-zone-localize': A parameter for setting the time zone |
| 400 | <time> is not a valid time to send (value of ‘o:time-zone-localize’) | The specified time is not a valid time to send the email | Choose a different, valid time to send the email | 'o:time-zone-localize': A parameter for setting the time zone |
| 400 | invalid delivery time format | The format of the delivery time is invalid | Correct the format of the delivery time | Delivery time: The time when the email should be delivered |
| 400 | to parameter is not a valid address. please check documentation | The receiver's email address is invalid | Check and correct the format of the receiver's email address | 'to' parameter: Receiver's email address |
| 400 | from parameter is not a valid address. please check documentation | The sender's email address is invalid | Check and correct the format of the sender's email address | 'from' parameter: Sender's email address |
| 400 | cc parameter is not a valid address. please check documentation | The CC email address is invalid | Check and correct the format of the CC email address | 'cc' parameter: Carbon copy email address |
| 400 | bcc parameter is not a valid address. please check documentation | The BCC email address is invalid | Check and correct the format of the BCC email address | 'bcc' parameter: Blind carbon copy email address |
| 400 | ‘recipient-variables’ parameter is not a valid JSON | The 'recipient-variables' parameter is not correctly formatted as JSON | Correct the format of the 'recipient-variables' parameter | 'recipient-variables' parameter: Variables specific to each recipient of the email |
| 400 | Domain example.com is not allowed to send: Sandbox subdomains are for test purposes only. Please add your own domain or add the address to authorized recipients in Account Settings. | The sender's domain is a sandbox subdomain, which are for testing only | Use a non-sandbox domain, or add the recipient to the list of authorized recipients | Sandbox domain: A domain for testing purposes |
| 400 | Domain example.com is not allowed to send: Free accounts are for test purposes only. Please upgrade or add the address to authorized recipients in Account Settings. | The sender's account is a free account, which is for testing only | Upgrade to a paid account, or add the recipient to the list of authorized recipients | Free account: An account that doesn't require payment |
| 400 | Domain example.com is not allowed to send: The domain is unverified and requires DNS configuration. Log in to your control panel to view required DNS records. | The sender's domain is unverified and needs DNS configuration | Verify the domain and configure the DNS as needed | DNS: Domain Name System, a system for translating domain names to IP addresses |
| 400 | Domain example.com is not allowed to send: Please activate your Mailgun account. Check your inbox or log in to your control panel to resend the activation email. | The sender's Mailgun account is not activated | Activate the Mailgun account by following the instructions in the activation email | Mailgun: A service for sending, receiving and tracking emails |
| 400 | is not a valid secondary dkim domain name | The provided secondary DKIM domain name is invalid | Check and correct the format of the secondary DKIM domain name | DKIM: DomainKeys Identified Mail, a method for verifying the authenticity of email senders |
| 401 | Forbidden | The user does not have the necessary permissions for the request | Ensure the user has the correct permissions for the request | Forbidden: A status code indicating the user doesn't have necessary permissions |
| 404 | Domain not found: example.com | The specified domain does not exist | Use a valid, existing domain | Domain: The part of an email address after the @ symbol |
| 403 | Domain example is not allowed to send large batches yet | The specified domain is not authorized to send large batches of emails | Request permission to send large batches, or send smaller batches | Batch: A group of emails sent as part of a single operation |
| 403 | Rejected: IP <id-address> can’t be used to send the message | The IP address of the sender is not allowed to send the message | Use a different, authorized IP address to send the message | IP address: A unique identifier for devices on a network |
| 413 | request size exceeds 52.4MiB limit | The size of the request exceeds the limit of 52.4MiB | Reduce the size of the request to under 52.4MiB | MiB: Mebibyte, a unit of digital storage |
| 429 | Domain example.com is not allowed to send: request limit exceeded, try again after Mon, 20 Dec 2021 20:33:21 UTC | The sender's domain has exceeded the limit for sending requests | Wait until the specified time, then try sending the request again | Request limit: The maximum number of requests that can be sent in a given time period |
| 429 | Domain example.com is not allowed to send: bytes limit exceeded, try again after Mon, 20 Dec 2021 20:33:21 UTC | The sender's domain has exceeded the limit for sending bytes | Wait until the specified time, then try sending the request again | Bytes limit: The maximum amount of data that can be sent in a given time period |
| 429 | Domain example.com is not allowed to send: recipient limit exceeded, try again after Mon, 20 Dec 2021 20:33:21 UTC | The sender's domain has exceeded the limit for number of recipients | Wait until the specified time, then try sending the request again | Recipient limit: The maximum number of recipients that can be addressed in a given time period |
| 500 | Internal Server Error | There is a problem with the server | Wait and try the request again later, or contact the server administrator | Internal Server Error: A general-purpose status code indicating a problem with the server |
Gmail / Google Workspace:
| Error Code | Meaning | Troubleshooting | Glossary |
| 421, "4.3.0" | Temporary System Problem. Try again later | Retry sending the message later | SMTP: Simple Mail Transfer Protocol, a protocol for sending e-mail messages |
| 421, "4.4.5" | The server is busy; try again later | Retry sending the message later | - |
| 421, "4.7.0" | IP not in whitelist for RCPT domain, closing connection | Check if your IP address is allowed to send emails to the receiver | RCPT: SMTP command to specify the recipient of the message |
| 421, "4.7.0" | Our system has detected an unusual rate of unsolicited mail originating from your IP address. | Review your sent emails for any potential unsolicited mail. | - |
| 421, "4.7.0" | Temporary System Problem. Try again later | Retry sending the message later | - |
| 421, "4.7.0" | TLS required for RCPT domain, closing connection | Make sure your system supports TLS (Transport Layer Security) | TLS: Protocol that provides communications security over a computer network |
| 421, "4.7.0" | Try again later, closing the connection | Retry sending the message later | DoS: Denial of Service, a cyber-attack that makes a machine or network resource unavailable |
| 450, "4.2.1" | The user you are trying to contact is receiving mail too quickly | Resend your message at a later time | - |
| 450, "4.2.1" | The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered. | Resend your message at a later time. | - |
| 450, "4.2.1" | Peak SMTP relay limit exceeded for customer | Try reducing the number of sent emails | SMTP relay: Process of transferring an email from one mail server to another |
| 451, "4.3.0" | The mailMail server temporarily rejected the message | Retry sending the message later | - |
| 451, "4.3.0" | Multiple destination domains per transaction is unsupported | Send your message to a single domain at a time | Domain: Part of the network address that represents a specific entity (like a company) on the internet |
| 451, "4.4.2" | Timeout - closing connection | Retry sending the message later | - |
| 451, "4.5.0" | SMTP protocol violation | Ensure that your system is correctly following the SMTP protocol | SMTP: Simple Mail Transfer Protocol, a protocol for sending e-mail messages |
| 452, "4.2.2" | The email account that you tried to reach is over quota | Ask the recipient to clear their inbox | Over quota: When a user has filled their storage limit |
| 452, "4.5.3" | Domain policy size per transaction exceeded | Try sending to the recipient in a separate transaction | - |
| 452, "4.5.3" | Your message has too many recipients | Reduce the number of recipients for your message | - |
| 454, "4.5.0" | SMTP protocol violation, no commands allowed to pipeline after STARTTLS. | Check your SMTP relay settings and try again. | STARTTLS: A way to take an existing insecure connection and upgrade it to a secure connection using SSL/TLS. |
| 454, "4.7.0" | Cannot authenticate due to a temporary system problem. | Try again later. If the problem persists, contact your email provider. | Authenticate: To verify the identity of a user, device, or system. |
| 501, "5.5.2" | Cannot decode the response. | This can be a server-side issue. Try again later or contact your service provider. | Decode: To convert from an encoded or encrypted form to plain text. |
| 501, "5.5.4" | HELO/EHLO argument is invalid. | Check your SMTP server configuration for errors. | HELO/EHLO: SMTP commands sent by an email server to identify itself when connecting to another email server. |
| 502, "5.5.1" | Too many unrecognized commands, goodbye. | Check your SMTP commands for any mistakes. | SMTP Commands: Instructions that an email client communicates to the mail server to send an email. |
| 502, "5.5.1" | Unimplemented command. | Ensure that your email client is using commands recognized by the SMTP server. | Unimplemented: Not yet put into effect. |
| 503, "5.5.1" | "EHLO/HELO first. | Your email client may be out of order. Ensure it starts with an EHLO or HELO command. | EHLO/HELO: Commands used by SMTP to initiate the connection. |
| 503, "5.5.1" | MAIL first. | The MAIL command needs to be the first command in your SMTP conversation. | MAIL: An SMTP command is used to initiate mail transfer. |
| 503, "5.5.1" | RCPT first. | The RCPT command needs to be the first command in your SMTP conversation. | RCPT: An SMTP command is used to identify the email's recipient. |
| 503, "5.7.0" | No identity changes are permitted. | Check your SMTP configuration or contact your service provider. | Identity: The unique identifier (often a username or email address) associated with a specific user. |
| 504, "5.7.4" | Unrecognized Authentication Type | Check your SMTP settings and ensure you're using a supported authentication type. | Authentication Type: The method used to verify a user's identity, such as password or OAuth. |
| 530, "5.5.1" | Authentication Required | Check that you're properly authenticated with your SMTP credentials. | Authentication: The process of verifying a user's identity. |
| 530, "5.7.0" | Must issue a STARTTLS command first | Ensure that your email client initiates the SMTP connection with a STARTTLS command. | STARTTLS: A way to take an existing insecure connection and upgrade it to a secure connection using SSL/TLS. |
| 535, "5.5.4" | Optional Argument not permitted for that AUTH mode | Check your SMTP settings, especially the AUTH command and its arguments. | AUTH: An SMTP command is used to authenticate the client to the server. |
| 535, "5.7.1" | Application-specific password required | Use an application-specific password if you have 2-Step Verification enabled. | Application-specific password: A password for applications not supporting logging in using 2-Step Verification. |
| 535, "5.7.1" | Please log in with your web browser and then try again | Log into your account via your web browser, then resend your email. | - |
| 535, "5.7.1" | Username and Password not accepted | Ensure that you're entering the correct username and password. If you're using 2-Step Verification, use an application-specific password. | - |
| 550, "5.1.1" | The email account that you tried to reach does not exist | Check the recipient's email address for typos or unnecessary spaces. | - |
| 550, "5.2.1" | The email account that you tried to reach is disabled | You cannot send an email to a disabled account. Contact the recipient through other means if possible. | - |
| 550, "5.2.1" | The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered | Try again later. | - |
| 550, "5.4.5" | Daily sending quota exceeded | Limit the number of emails you send each day or upgrade your Google Workspace edition if you need to send more mail. | Quota: A set limit on how much of a particular resource a user or program can use. |
| 550, "5.4.5" | Daily SMTP relay limit exceeded for user | Check your SMTP relay settings or upgrade your Google Workspace edition to send more mail. | SMTP relay: A service used to send large volumes of email. |
| 550, "5.7.0" | Mail relay denied | The email was not sent because the SMTP relay was denied; contact your service provider. | Relay: The act of passing email from one server to another. |
| 550, "5.7.0" | Mail Sending denied | Ensure the sender account is active and part of your Google Workspace domain. | - |
| 550, "5.7.1" | Email quota exceeded | You'll need to free up storage space or purchase more in order to send additional emails. | Quota: A set limit on how much of a particular resource a user or program can use. |
| 550, "5.7.1" | Invalid credentials for relay | Check the configuration of your SMTP relay service. | Credentials: Information that includes identification and proof of identification used to gain access to resources. |
| 550, "5.7.1" | Our system has detected an unusual rate of unsolicited mail originating from your IP address. | If you're not sending spam, examine your network for malware or misconfigured software. | Unsolicited mail: Email that a user did not ask for (usually refers to spam). |
| 550, "5.7.1" | Our system has detected that this message is likely unsolicited mail. To reduce the amount of spam sent to Gmail, this message has been blocked | Ensure the email complies with Gmail’s Bulk Email Senders Guidelines | Unsolicited mail: Email that a user did not ask for (usually refers to spam). |
| 550, "5.7.1" | The IP you're using to send mail is not authorized to send email directly to our servers | Use the SMTP relay at your service provider instead | SMTP relay: A service used to send large volumes of email. |
| 550, "5.7.1" | The user or domain that you are sending to (or from) has a policy that prohibits the mail that you sent | Review the email content and contact the domain administrator for further details. | Policy: A rule or set of rules governing how systems or organizations operate. |
| 550, "5.7.1" | Unauthenticated email is not accepted from this domain | Check your SMTP settings and ensure the email passes SPF or DKIM authentication | Unauthenticated email: An email that hasn't passed validation checks to prove it came from the domain it claims to be from. |
| 550, "5.7.1" | Daily SMTP relay limit exceeded for customer | Check your SMTP relay settings or upgrade your Google Workspace edition if you need to send more mail | SMTP relay: A service used to send large volumes of email. |
| 550, "5.7.26" | Unauthenticated email from domain name is not accepted due to domain's DMARC policy. | Adjust your DMARC records, consider using a service like Google Workspace to send your mail, and contact the administrator of the receiving mail server. | DMARC: An email validation system that detects and prevents email spoofing. |
| 550, "5.7.26" | This message does not have authentication information or fails to pass authentication checks. | Ensure the email passes SPF or DKIM authentication | Authentication: The process of verifying the identity of a user, process, or device. |
| 550, "5.7.26" | This message fails to pass SPF checks for an SPF record with a hard fail policy. | Adjust your SPF records and ensure the email passes SPF authentication | SPF (Sender Policy Framework): An email authentication method designed to detect forging sender addresses during email delivery. |
| 552, "5.2.2" | The email account that you tried to reach is over quota | Ask the recipient to clear some space in their inbox | Quota: A set limit on how much of a particular resource a user or program can use. |
| 552, "5.2.3" | Your message exceeded Google's message size limits | Reduce the size of the message and try again | - |
| 553, "5.1.2" | We weren't able to find the recipient domain | Double-check the recipient's email address for typos or unnecessary spaces | Domain: The part of an email address that comes after the @ symbol. |
| 554, "5.6.0" | The mail message is malformed. Not accepted | Check the format of your email and try again | Malformed: Structured incorrectly or in a way that does not conform to the expected format. |
| 554, "5.6.0" | Message exceeded 50 hops; this may indicate a mail loop | Check your SMTP settings to prevent potential mail loops | Mail Loop: A situation in which an email message is continually bounced back and forth between two or more servers. |
| 554, "5.7.0" | This message was blocked because its content presents a potential security issue. | Ensure the content and attachments of the email comply with Google’s policies. | - |
| 554, "5.7.0" | IP has been blacklisted due to spam activity | Contact your service provider and take steps to remove your IP from the blacklist. | Blacklist: A list of entities blocked or denied access to a certain system or protocol. |
| 554, "5.7.1" | The transaction failed because the recipient's mailbox is full | Ask the recipient to clear some space in their mailbox | Mailbox: An electronic folder where incoming emails are stored for a user. |
| 554, "5.7.1" | The message you're trying to send exceeds the recipient's size limits | Reduce the size of the message or contact the recipient to increase their size limits | Size limits: Restrictions on the maximum size of an email message or attachment. |
| 555, "5.5.2" | Syntax error | Check the syntax of the email addresses, commands, or configuration settings. | Syntax: The set of rules that dictate the structure and format of a language or code. |
| 555, "5.5.4" | Optional Argument not permitted for that AUTH mode | Review your SMTP authentication settings and ensure they are correctly configured | Authentication: The process of verifying the identity of a user, process, or device. |
| 555, "5.7.1" | Authentication required for relay | Provide valid authentication credentials for the SMTP relay | Relay: Forwarding email messages from one mail server to another. |
| 555, "5.7.1" | Please log in with your web browser and then try again | Access your Gmail account via a web browser and follow any on-screen prompts to resolve the issue | Web browser: A software application used to access and view websites. |
| 555, "5.7.1" | Username and Password not accepted | Verify the correctness of your username and password, and ensure they are correctly entered. | Username: A unique identifier used to access a system or service. |
| 550, "5.1.1" | The email account that you tried to reach does not exist | Double-check the recipient's email address for typos, or contact the recipient to confirm the correct email address | Typos: Errors or mistakes in the spelling or formatting of text. |
| 550, "5.2.1" | The email account that you tried to reach is disabled | Verify the status of the recipient's email account or contact the recipient to confirm the account status | Disabled: Inactive or deactivated. |
| 550, "5.4.5" | Daily sending quota exceeded | Reduce the number of outgoing emails or upgrade your Google Workspace edition for higher sending quotas. | I am sending quota: The maximum number of emails allowed to be sent within a specified time period. |
| 550, "5.4.5" | Daily SMTP relay limit exceeded for user | Check your SMTP relay sending limits or contact your administrator for assistance | SMTP relay: A service used to send large volumes of email. |
| 550, "5.7.0" | Mail relay denied | Check your SMTP relay settings and ensure they comply with Google's policies. | Mail relay: Forwarding email messages from one mail server to another. |
| 550, "5.7.0" | Mail Sending denied. This error occurs if the sender account is disabled or not registered within your Google Workspace domain. | Verify the sender's email account status and ensure it is enabled and registered within the Google Workspace domain. | Domain: A group of computers or devices that share a common set of rules and settings. |
| 550, "5.7.1" | Email quota exceeded | Reduce your mailbox size or upgrade your Google Workspace edition for higher storage quotas. | Quota: The allocated amount or limit for a particular resource or service. |
| 550, "5.7.1" | Invalid credentials for relay | Verify the correctness of your authentication credentials for the SMTP relay. | Credentials: Information used to verify one's identity or access a system. |
| 550, "5.7.1" | Our system has detected an unusual rate of unsolicited mail originating from your IP address. | Check your network for malware or misconfigured software to prevent spamming activities. | Unsolicited mail: Email that is sent without the recipient's explicit consent. |
| 550, "5.7.1" | Our system has detected that this message is likely unsolicited mail | Ensure your email content and attachments comply with Google's spam policies to prevent message blocking | Spam: Unsolicited or unwanted email, often sent in bulk. |
| 550, "5.7.1" | The IP you're using to send mail is not authorized to send emails directly to our servers. | Use the SMTP relay provided by your service provider to send an email or contact Google support for further assistance | SMTP: Simple Mail Transfer Protocol, the standard protocol used for email transmission. |
| 550, "5.7.1" | The user or domain that you are sending to (or from) has a policy that prohibits the mail that you sent | Review and comply with the policies of the recipient's user or domain to ensure successful email delivery. | Policies: Rules or guidelines that govern the behavior or actions within a system or organization. |
| 550, "5.7.1" | Unauthenticated email is not accepted from this domain | Configure your email client or server to authenticate before sending emails | Authentication: The process of verifying the identity or legitimacy of a user or entity. |
| 550, "5.7.1" | Daily SMTP relay limit exceeded for customer | Review your SMTP relay sending limits or contact your administrator for assistance. | SMTP relay: A service used to send large volumes of email. |
| 550, "5.7.26" | Unauthenticated email from domain name is not accepted due to domain's DMARC policy | Authenticate your email with the appropriate mechanisms specified by the DMARC policy of the recipient's domain. | DMARC: Domain-based Message Authentication, Reporting, and Conformance, a security protocol for preventing email spoofing. |
| 550, "5.7.26" | This message does not have authentication information or fails to pass authentication checks (SPF or DKIM) | Ensure your email passes SPF and DKIM authentication checks to improve deliverability. | SPF: Sender Policy Framework, a protocol that validates the origin of email messages. DKIM: DomainKeys Identified Mail, a method for validating the authenticity of email messages. |
| 552, "5.2.2" | The email account that you tried to reach is over quota | Advise the recipient to free up space in their mailbox by deleting unnecessary emails | Quota: The allocated storage capacity for an email account. |
| 552, "5.2.3" | Your message exceeded Google's message size limits | Reduce the size of your email message or use alternative methods for sharing large files | Message size limits: The maximum allowed size for an email message, including attachments. |
| 553, "5.1.2" | We weren't able to find the recipient domain | Verify the correctness of the recipient's email address and check for any typos or formatting errors. | Domain: The part of an email address after the "@" symbol indicating the recipient's email server. |
| 554, "5.6.0" | The mail message is malformed. Not accepted | Review the structure and content of your email message for any errors or inconsistencies. | Malformed: Incorrectly structured or formatted. |
| 554, "5.6.0" | Message exceeded 50 hops; this may indicate a mail loop | Investigate and resolve any circular forwarding or routing configurations causing the mail loop | Mail loop: A situation where an email is continuously forwarded or routed between multiple recipients. |
| 554, "5.7.0" | Too Many Unauthenticated commands | Review your SMTP authentication settings and ensure proper authentication during the SMTP session. | Unauthenticated commands: SMTP commands are issued without proper authentication. |
| 555, "5.5.2" | Syntax error | Double-check the syntax and format of email addresses, commands, or configuration settings. | Syntax: The rules and structure that govern the correct arrangement of elements in a language or code. |
Outlook
| Error Category | Error Codes | Meaning | Troubleshooting | Glossary |
| General Errors | 0x800CCC00 | This error suggests that the authentication did not load, which might be a result of invalid login details or a problem with the server. | Recheck your email and password details to ensure they are correct. If the problem persists, try restarting your mail server or contact your ISP for support. | ISP: Internet Service Provider |
| General Errors | 0x800CCC01 | Invalid certificate content - the certificate content that Outlook is trying to use for a secured connection is invalid. | Verify that all necessary intermediate certificates are installed. If the certificate is self-signed, make sure that the same certificate is installed on both the client and server machines. | Intermediate certificates: These are certificates that are part of the certification path. They connect your certificate to the root certificate of the certificate authority. |
| General Errors | 0x800CCC02 | This indicates an invalid certificate date. | Check the certificate's validity period. It might have expired, in which case you need to renew it. | Certificate validity period: The time frame in which a certificate is considered valid. Once expired, it must be renewed. |
| General Errors | 0x800CCC03 | User already connected. This means there's another session that's already connected to the mail server. | Disconnect the other session or try again later. Check for multiple instances of Outlook. | Session: A session represents a single period of user interaction with your app. |
| General Errors | 0x800CCC04 | - | - | - |
| General Errors | 0x800CCC05 | This suggests that Outlook is not connected to the server. | Check your internet connection. If it is stable, there might be issues with the server. Contact your ISP for help. | Server: A server is a computer that provides data to other computers. |
| General Errors | 0x800CCC06 | - | - | - |
| General Errors | 0x800CCC07 | - | - | - |
| General Errors | 0x800CCC08 | - | - | - |
| General Errors | 0x800CCC09 | - | - | - |
| General Errors | 0x800CCC0A | Message download incomplete - this happens when Outlook is unable to fully download an email message from the server. | Check your internet connection or try deleting and re-downloading the email. | Download: The process of getting data from a server to your device. |
| General Errors | 0x800CCC0B | Server or maildrop is busy. This suggests that the server is overwhelmed with requests. | Try again later when the server might be less busy. If the problem persists, it could be a server-side issue and you might need to contact your ISP. | Maildrop: A maildrop is a location where mail is stored until it is collected. |
| General Errors | 0x800CCC0C | - | - | - |
| General Errors | 0x800CCC0D | Cannot locate server. This means Outlook is unable to establish a connection with your mail server. | Check your server settings, ensure that you have the correct server address, and that your internet connection is active. | Server settings: These are the specific requirements and information needed to connect to a server. |
| General Errors | 0x800CCC0E | Cannot connect to server. A connection could not be made to the email server. | Check your internet connection, firewall settings and server settings. If everything appears to be correct, there could be a server-side issue. | Firewall: This is a network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules. |
| General Errors | 0x800CCC0F | Connection dropped - this means the connection to the server was interrupted. | Check your internet connection, and ensure your email settings are correct. If the problem persists, it could be a server-side issue. | Server-side: This refers to operations that are performed by the server in a client-server relationship. |
| General Errors | 0x800CCC10 | Invalid address - this error occurs when the email address is not valid or correctly entered. | Double-check the email address for any errors or missing information. | Email address: This is an identifier for an email box to which email messages are delivered. |
| General Errors | 0x800CCC11 | Invalid address list - the list of addresses is not valid. | Check to make sure all the addresses in your list are formatted correctly and remove any that are not. | Address list: This is a collection of mail-enabled recipient objects in Exchange Online. |
| General Errors | 0x800CCC12 | Socket read error - this occurs when Outlook cannot read from the network. | Check your network connection. If the problem persists, try restarting your computer or contact your ISP. | Socket: A socket represents a single connection between two network applications. |
| General Errors | 0x800CCC13 | Socket write error - this occurs when Outlook cannot write data to the network. | Check your network connection. If the problem persists, try restarting your computer or contact your ISP. | Write: In computing, writing data refers to the process of entering data into a computer system or storage medium. |
| General Errors | 0x800CCC14 | Socket initialization error - this error occurs when Outlook cannot initialize the network connection. | Check your network settings, and ensure your internet connection is active. If the problem persists, try restarting your computer or contact your ISP. | Initialization: The process of locating and using the defined values for variable data that is used by a computer program. |
| General Errors | 0x800CCC15 | Socket connect error - this error means that Outlook cannot establish a network connection. | Check your network connection and settings. If the problem persists, try restarting your computer or contact your ISP. | Network connection: This refers to the setup that allows the exchange of data between two or more network devices. |
| General Errors | 0x800CCC16 | Invalid account - the user account on the mail server is invalid. | Verify your account details with your email provider. Ensure you are entering the correct username and password. | User account: This is a location on a network server where a user has access to personal files and settings. |
| General Errors | 0x800CCC17 | User canceled operation - the user canceled the operation before it was complete. | If you did not intentionally cancel the operation, try again. If the problem persists, there may be an issue with your email client or ISP. | Email client: This is an application used to manage a user's email. |
| General Errors | 0x800CCC18 | Logon failure: unknown user name or bad password - the username or password is incorrect. | Re-enter your username and password carefully to ensure they are correct. If the problem persists, you may need to reset your password or contact your ISP. | Logon: This is the process of gaining access to a computer system or network by entering a username and password. |
| General Errors | 0x800CCC19 | Timeout - this error occurs when a network operation in Outlook times out. | Check your network connection. If it is stable, the server might be slow or overloaded. Try again later. | Timeout: This is a designated amount of time that a program or system will wait for a response before it gives up. |
| General Errors | 0x800CCC1A | Security error - this means that there's a problem with the SSL or TLS security protocols. | Make sure you're using the correct security settings in your email client. If necessary, you can temporarily disable SSL/TLS to see if that's causing the problem. | SSL/TLS: These are cryptographic protocols designed to provide secure communication over a computer network. |
| General Errors | 0x800CCC1B | Server does not support the requested encryption type - the server doesn't support the encryption method specified in your email client. | Make sure your email client's encryption settings match what your email server supports. You may need to contact your email provider for the correct settings. | Encryption: This is the method by which information is converted into a secret code that hides the information's true meaning. |
| General Errors | 0x800CCC1C | Not able to access the account - the user can't access the email account. | Double check your username and password. If you're certain they're correct, your email account might be temporarily locked or there might be a problem with the mail server. | Mail server: This is a computerized system that sends and receives email. |
| General Errors | 0x800CCC1D | No server response - the server isn't responding to requests. | This might be a temporary problem with the mail server. If it persists, contact your email provider. | Server response: This refers to the reply by the server after it has processed the client's request. |
| General Errors | 0x800CCC1E | Unable to connect to the account - the email client can't connect to the email account. | Double check your email client settings, including username, password, and mail server. If everything seems correct, there might be a problem with the mail server. | Connect: This refers to establishing a network connection for communication between devices. |
| General Errors | 0x800CCC1F | Server response timeout - the server took too long to respond. | This is typically a problem with the server. You could try to connect again later, or contact your email provider if the problem persists. | Server response timeout: This is when the server fails to respond to a request from a client within a given time period. |
| General Errors | 0x800CCC20 | Unable to find the email server - the email client can't find the mail server. | Make sure you've entered the correct server address in your email client settings. If the problem persists, contact your email provider. | Server address: This is the unique identification of a server, often an IP address or a URL. |
| General Errors | 0x800CCC21 | Server response error - the server responded with an error. | The exact problem will depend on the error message. It could be a temporary server problem, or it might indicate a problem with your email client settings. | Error message: This is a message displayed when an unexpected condition occurs, usually on a computer or other device. |
| General Errors | 0x800CCC22 | Server response fail - this means the server has failed to respond as expected. | Try again later, as this could be a temporary server issue. If the problem persists, contact your email provider. | Server response: This refers to the server's reply after processing the client's request. |
| General Errors | 0x800CCC23 | Authentication failed - the email client has failed to authenticate with the email server. | Check your email client settings, including username and password. If they are correct, contact your email provider. | Authentication: This is the process of verifying the identity of a user or system. |
| General Errors | 0x800CCC24 | Network connection failure - there is a problem with the network connection. | Check your internet connection. If other internet-based applications are working fine, the problem might lie with your email server. | Network connection: This refers to the link between two or more computers or systems allowing them to share resources. |
| General Errors | 0x800CCC25 | SSL connection failure - the SSL connection to the email server has failed. | Make sure your email client is correctly configured for SSL. If necessary, you can temporarily disable SSL to see if that's causing the problem. | SSL: Secure Sockets Layer, a protocol for web browsers and servers that allows for the authentication, encryption and decryption of data sent over the Internet. |
| General Errors | 0x800CCC26 | Unknown error - an unspecified error has occurred. | As this error is quite generic, there could be various potential causes. Restart your email client, and if the problem persists, contact your email provider. | Unknown error: An error where the root cause is not identified. |
| General Errors | 0x800CCC27 | Out of memory - there isn't enough memory to complete the requested task. | Close unnecessary applications to free up memory. If the problem persists, your computer might not have enough memory to run your email client. | Out of memory: A condition where a system lacks sufficient memory to perform a task. |
| General Errors | 0x800CCC28 | Server doesn't support digital IDs - the email server doesn't support the digital ID feature. | This error typically requires a change in server settings. You might need to contact your email provider for help. | Digital ID: A digital equivalent of identification documents in physical form. |
| General Errors | 0x800CCC29 | User not authenticated on server - the server has not authenticated the user. | Re-enter your username and password in your email client. If they're correct and you're still getting this error, you might need to contact your email provider. | User authentication: The process of confirming a user's identity. |
| Winsock Errors | 0x800CCC40 | Network subsystem is unusable. | Try restarting your machine or reset your network settings. If the problem persists, you might need to check your network hardware or contact your ISP. | Network subsystem: It refers to the part of the operating system that is responsible for networking. |
| Winsock Errors | 0x800CCC41 | Windows Sockets cannot support this application. | Make sure that the application you are trying to run is compatible with your version of Windows. If necessary, look for an updated version of the application. | Windows Sockets (Winsock): It is a technical specification that defines how Windows network software should access network services, especially TCP/IP. |
| Winsock Errors | 0x800CCC42 | - | (As no specific description is given, generic advice would be to restart your machine and check for system updates.) | - |
| Winsock Errors | 0x800CCC43 | Bad address. | The error suggests that the address provided is invalid. Check the IP address you're using and ensure it's correct. | IP address: An Internet Protocol address is a numerical label assigned to each device participating in a computer network that uses the Internet Protocol for communication. |
| Winsock Errors | 0x800CCC44 | Unable to load Windows Sockets. | Reinstall your network adapter drivers, and/or reset your network settings. If the problem persists, you might need to reinstall your operating system. | Network adapter drivers: These are software programs that enable a computer to communicate with a network. |
| Winsock Errors | 0x800CCC45 | Operation now in progress. This error appears if a Windows Sockets API is called while a blocking function is in progress. | Do not run blocking operations in parallel with other functions. Consider reorganizing your code to avoid this conflict. | Blocking operation: A function or process that stops the execution of the program until a particular condition is met. |
| SMTP Errors | 0x800CCC60 | Invalid response. | Check your server settings and verify that you're connecting to the correct server. If you're using an email client, try re-configuring the SMTP server settings. | SMTP: Simple Mail Transfer Protocol, a protocol for sending e-mail messages between servers. |
| SMTP Errors | 0x800CCC61 | Unknown error code. | As this is an unspecified error, try restarting your email client or your computer. If the problem persists, reach out to your email provider for assistance. | - |
| SMTP Errors | 0x800CCC62 | Syntax error returned. | This error is generally related to incorrect email format or structure. Check the email you're trying to send for any unusual characters or structures and correct them. | Syntax error: A character or string incorrectly placed in a command or instruction, which causes a failure in execution. |
| SMTP Errors | 0x800CCC63 | Parameter syntax incorrect. | Ensure the command sent to the SMTP server is correct and follows the correct syntax. This could be related to email content or configuration settings. | Parameter: A value that the user provides to a command. |
| SMTP Errors | 0x800CCC64 | Command not implemented. | The command sent to the SMTP server may not be supported. Check the compatibility and requirements of your SMTP server. | Command: A directive to a computer program acting as an interpreter of some kind, in order to perform a specific task. |
| SMTP Errors | 0x800CCC65 | Improper command sequence. | Commands were sent to the SMTP server in the wrong order. Ensure the sequence of commands sent to the SMTP server is correct. | - |
| SMTP Errors | 0x800CCC66 | Command not implemented. | The command sent to the SMTP server may not be supported. Check the compatibility and requirements of your SMTP server. | - |
| SMTP Errors | 0x800CCC67 | Command not available. | The requested command is not available in the current context or server. Check if the server supports the command or if you're in the correct stage of the SMTP process. | - |
| SMTP Errors | 0x800CCC68 | Mailbox is locked and busy. | Wait a while and try again. If the problem persists, reach out to your email provider for assistance. | Mailbox: A destination to which email messages are delivered. It is usually associated with a single user. |
| SMTP Errors | 0x800CCC69 | Mailbox not found. | Ensure the recipient email address is correct. If it's correct and the issue persists, the recipient's email server may be misconfigured. | - |
| SMTP Errors | 0x800CCC6A | Error processing request. | This is a server-side issue. The server had a problem processing the request. Try again later. If the problem persists, contact your email service provider. | - |
| SMTP Errors | 0x800CCC6B | User mailbox is known but mailbox not on this server. | The email address you're trying to reach is valid, but the server you're connected to doesn't host the mailbox. Ensure your server settings are correct. | - |
| SMTP_551_ USER_NOT_ LOCAL | 0x800CCC6C | No space to store messages. | The recipient's mailbox may be full. You can try again later or contact the recipient to ask them to free up some space in their mailbox. | SMTP: Simple Mail Transfer Protocol, the protocol used in sending and receiving e-mail. |
| SMTP_551_USER_NOT_LOCAL | 0x800CCC6D | Storage limit exceeded. | This error is typically a server side issue. It means the mailbox storage has been exceeded due to which the mail could not be sent. You can try again later, or contact your server admin/ISP. | SMTP: Simple Mail Transfer Protocol, ISP: Internet Service Provider. |
| SMTP_551_USER_NOT_LOCAL | 0x800CCC6E | Invalid mailbox name syntax. | The syntax of the recipient's email address is not correct. Verify the email address and try again. | SMTP: Simple Mail Transfer Protocol, the protocol used in sending and receiving e-mail. |
| SMTP_551_USER_NOT_LOCAL | 0x800CCC6F | Transaction failed. | This error generally indicates a failure in the transmission of the email. It could be due to a variety of issues, including server problems, network issues, or email client problems. Check your internet connection, server settings, and email client settings. | SMTP: Simple Mail Transfer Protocol, the protocol used in sending and receiving e-mail. |
| SMTP_551_USER_NOT_LOCAL | 0x800CCC78 | Unknown sender. This is caused by having the incorrect e-mail address in the Reply-To field. | Verify the 'Reply-To' field in your email. It may be incorrectly filled. Make sure it is a valid email address and try sending again. | SMTP: Simple Mail Transfer Protocol, the protocol used in sending and receiving e-mail. |
| SMTP_REJECTED_SENDER | 0x800CCC79 | Server rejected recipients. | This error usually occurs when the recipients' email addresses are not accepted by the server. Verify the recipients' email addresses, ensure they are valid and properly formatted, and try again. | SMTP: Simple Mail Transfer Protocol, the protocol used in sending and receiving e-mail. |
| SMTP_REJECTED_SENDER | 0x800CCC7A | No sender address specified. | This error occurs when there is no sender address specified in the email. Check your email client settings and make sure that your email address is correctly entered in the outgoing mail server settings. | |
| SMTP_REJECTED_SENDER | 0x800CCC7B | No recipients specified. | This error happens when no recipient email addresses have been specified. You need to specify at least one valid recipient email address before sending the email. | |
| POP3 Errors | 0x800420CB | Mail cannot be stored on server. | This error occurs when the POP3 server is unable to store the incoming mail. Check the server settings, mailbox quota, and available storage space. Contact your email provider for assistance if needed. | POP3: Post Office Protocol 3, a standard protocol used for retrieving e-mails from a remote server. |
| POP3 Errors | 0x800CCC90 | Client response invalid. | This error indicates that the client response sent to the POP3 server is invalid or not recognized. Review the client configuration, ensure correct settings, and check for any software conflicts or network issues. | - |
| POP3 Errors | 0x800CCC91 | Invalid user name or user not found. | This error occurs when the provided username for the POP3 server is invalid or the user does not exist. Double-check the username, ensure it is entered correctly, and verify that the user account exists on the server. | - |
| POP3 Errors | 0x800CCC92 | Password not valid for account. | The error indicates an incorrect password provided for the POP3 account. Make sure the password is correct and properly entered. If necessary, reset the password and update the account settings in the email client. | - |
| POP3 Errors | 0x800CCC93 | Unable to interpret response. | This error suggests that the client is unable to interpret the response received from the POP3 server. Review the client configuration, ensure proper settings, and check for any software conflicts or network issues. | - |
| POP3 Errors | 0x800CCC94 | STAT Command required. | The POP3 server requires the STAT command to be executed before performing any further operations. Make sure the client is issuing the STAT command to retrieve the necessary information. | STAT Command: A command in POP3 that retrieves the status of the mailbox, including the number of messages and the total size. |
| POP3 Errors | 0x800CCC95 | No messages on server. | This error indicates that there are no messages available on the POP3 server. Check if any new messages are present in the mailbox or contact your email provider for assistance. | - |
| POP3 Errors | 0x800CCC96 | No messages marked for retrieval. | The error occurs when there are no messages marked for retrieval on the POP3 server. Ensure that messages are marked correctly for retrieval and try again. | - |
| POP3 Errors | 0x800CCC97 | Message ID out of range. | This error suggests that the requested message ID is out of range or does not exist on the POP3 server. Check the message ID and verify its availability on the server. | - |
| IMAP Errors | 0x800CCCD1 | Login failed. | The login attempt to the IMAP server has failed. Double-check the username and password, ensure they are correct, and verify that the server settings are accurate. If the issue persists, contact your email provider for further assistance. | IMAP: Internet Message Access Protocol, a standard protocol used for accessing and retrieving e-mails from a remote server. |
| IMAP Errors | 0x800CCCD2 | Message tagged. | This error indicates that the server has tagged the message but is not providing a response. Check the server status, network connection, and email client configuration. Retry the operation after ensuring a stable connection. | - |
| IMAP Errors | 0x800CCCD3 | Invalid response to request. | The server has returned an invalid response to the IMAP request. Verify the request sent by the client, check for any syntax errors or issues with the request format. Ensure the email client is compatible with the server's IMAP version. | - |
| IMAP Errors | 0x800CCCD4 | Syntax error. | The server has encountered a syntax error in the command or response. Review the command or response syntax, ensure it complies with the IMAP protocol specifications. Correct any syntax errors in the client configuration or request. | - |
| IMAP Errors | 0x800CCCD5 | Not an IMAP server. | The server being accessed is not recognized as an IMAP server. Verify the server settings, ensure the correct protocol (IMAP) is selected, and confirm the server's compatibility with IMAP. | - |
| IMAP Errors | 0x800CCCD6 | Buffer limit exceeded. | The IMAP server has exceeded the buffer limit. This can happen if the server is receiving a large amount of data or if there is an issue with the server configuration. Contact your email provider or system administrator for further assistance. | - |
| IMAP Errors | 0x800CCCD7 | Recovery error. | An error occurred during the recovery process. This can happen if the server is experiencing issues or if there is a problem with the mailbox. Contact your email provider for assistance in resolving the recovery error. | - |
| IMAP Errors | 0x800CCCD8 | Incomplete data. | The server has provided an incomplete response or data. Check the network connection, verify the server status, and ensure there are no interruptions or issues with the communication between the client and server. | - |
| IMAP Errors | 0x800CCCD9 | Connection not allowed. | The IMAP connection is not allowed by the server. This can occur due to server configuration or security restrictions. Contact your email provider or system administrator to verify the connection settings and permissions. | - |
| IMAP Errors | 0x800CCCDA | Unknown response. | The server has returned an unknown or unrecognized response. Check the request sent by the client, verify the server compatibility, and ensure the client configuration is correct. If the issue persists, contact your email provider for further assistance. | - |
| IMAP Errors | 0x800CCCDB | User ID has changed. | The user ID associated with the IMAP account has changed. Review the user ID and update it in the email client's account settings. Contact your email provider if you are unsure about the correct user ID to use. | - |
| IMAP Errors | 0x800CCCDC | User ID command failed. | The command related to the user ID has failed on the IMAP server. Verify the user ID command syntax, ensure it complies with the IMAP protocol. Check for any issues with the server configuration or network connectivity. | - |
| IMAP Errors | 0x800CCCDD | Unexpected disconnect. | The connection to the IMAP server was unexpectedly disconnected. Check the network connection, ensure there are no interruptions or network issues. Retry the operation and monitor for any further disconnects. | - |
| IMAP Errors | 0x800CCCDE | Invalid server state. | The IMAP server is in an invalid or improper state. This can happen due to server issues or conflicts. Contact your email provider or system administrator for assistance in resolving the server state issue. | - |
| IMAP Errors | 0x800CCCDF | Unable to authorize client. | The client is unable to authorize with the IMAP server. Check the client's authentication settings, ensure the username and password are correct. Verify that the server supports the chosen authentication method. Contact your email provider for further assistance. | - |
| IMAP Errors | 0x800CCCE0 | No more authorization types. | The IMAP server does not support any more available authorization types. Verify the client's authentication settings, ensure the selected authorization type is supported by the server. Contact your email provider for further guidance. | - |
| NNTP Errors | 0x800CCCA0 | News server response error. | This error indicates an error in the response received from the NNTP server. Check the network connection, verify server settings, and ensure proper authentication if required. Retry the operation after ensuring a stable connection. | - |
| NNTP Errors | 0x800CCCA1 | Newsgroup access failed. | The access to the newsgroup on the NNTP server has failed. Ensure the newsgroup exists, check the server settings, and verify that the client has appropriate permissions. Contact your news server provider for further assistance if needed. | - |
| NNTP Errors | 0x800CCCA2 | LIST command to server failed. | The LIST command issued to the NNTP server has failed. Review the command syntax, verify the server compatibility, and check for any network connectivity issues. Retry the command after ensuring a stable connection. | LIST Command: A command in NNTP that retrieves a list of available newsgroups on the server. |
| NNTP Errors | 0x800CCCA3 | Unable to display list. | This error suggests that the client is unable to display the list of newsgroups on the NNTP server. Check the client configuration, verify the server compatibility, and ensure proper authentication if required. Retry the operation after ensuring a stable connection. | - |
| NNTP Errors | 0x800CCCA4 | Unable to open group. | The client is unable to open a specific newsgroup on the NNTP server. Verify the newsgroup name, check the server settings, and ensure proper permissions to access the newsgroup. Contact your news server provider for further assistance if needed. | - |
| NNTP Errors | 0x800CCCA5 | Group not on server. | This error indicates that the requested newsgroup is not available on the NNTP server. Verify the newsgroup name, ensure it exists on the server, and check for any spelling errors. Contact your news server provider for further assistance if needed. | - |
| NNTP Errors | 0x800CCCA6 | Message not on server. | The requested message is not available on the NNTP server. Check the message ID, verify its existence on the server, and ensure proper command syntax. Contact your news server provider for further assistance if needed. | - |
| NNTP Errors | 0x800CCCA7 | Message header not found. | This error suggests that the header of the requested message is not found on the NNTP server. Check the message ID, verify its availability, and ensure proper command syntax. Contact your news server provider for further assistance if needed. | - |
| NNTP Errors | 0x800CCCA8 | Message body not found. | The body of the requested message is not found on the NNTP server. Check the message ID, verify its availability, and ensure proper command syntax. Contact your news server provider for further assistance if needed. | - |
| NNTP Errors | 0x800CCCA9 | Unable to post to server. | The client is unable to post or submit a message to the NNTP server. Check the client configuration, verify server settings, and ensure proper authentication if required. Retry the operation after ensuring a stable connection. | - |
| NNTP Errors | 0x800CCCAA | Unable to post to server. | This error indicates that the client is unable to post or submit a message to the NNTP server. Check the client configuration, verify server settings, and ensure proper authentication if required. Retry the operation after ensuring a stable connection. | - |
| NNTP Errors | 0x800CCCAB | Unable to display date. | The client is unable to display the date of a specific message on the NNTP server. Verify the message ID, check for any server issues, and ensure proper command syntax. Contact your news server provider for further assistance if needed. | - |
| NNTP Errors | 0x800CCCAC | Unable to display headers. | This error suggests that the client is unable to display the headers of a specific message on the NNTP server. Verify the message ID, check for any server issues, and ensure proper command syntax. Contact your news server provider for further assistance if needed. | - |
| NNTP Errors | 0x800CCCAD | Unable to display MIME headers. | The client is unable to display the MIME headers of a specific message on the NNTP server. Verify the message ID, check for any server issues, and ensure proper command syntax. Contact your news server provider for further assistance if needed. | - |
| NNTP Errors | 0x800CCCAE | Invalid user or password. | This error indicates that the provided user or password is invalid for the NNTP server. Verify the user credentials, check for any spelling errors, and ensure proper authentication. Contact your news server provider for further assistance if needed. | - |
| RAS Errors | 0x800CCCC2 | RAS/DUN not installed. | This error indicates that the Remote Access Service (RAS) or Dial-Up Networking (DUN) is not installed on the system. Install the necessary components or enable the required services for RAS/DUN functionality. | - |
| RAS Errors | 0x800CCCC3 | RAS/DUN process not found. | The RAS/DUN process is not found on the system. Verify that the required processes are running or restart the system to ensure the proper initialization of RAS/DUN components. | - |
| RAS Errors | 0x800CCCC4 | RAS/DUN error returned. | This error suggests that an error was returned by the RAS/DUN process. Check the specific error code or description associated with the error to determine the cause. Troubleshoot based on the specific error returned by the RAS/DUN process. | - |
| RAS Errors | 0x800CCCC5 | ConnectOID damaged or missing. | This error indicates that the ConnectOID used for connection is damaged or missing. Verify the configuration settings, check for any missing or corrupted files related to ConnectOID, and ensure proper initialization of the connection settings. | ConnectOID: Connect Object Identifier, a unique identifier used for establishing connections. |
| RAS Errors | 0x800CCCC6 | Error getting dial settings. | This error suggests that there was an error while retrieving the dial-up settings. Verify the dial-up configuration, check for any issues with the network adapter or modem, and ensure proper settings for establishing a dial-up connection. | - |
| Enhanced Mail System Status Codes | X.0.0 | Other undefined Status | The specific status code is not defined or recognized. Check for any additional error details or consult the relevant RFC document. | - |
| Enhanced Mail System Status Codes | X.1.0 | Other address status | The address status is unknown or not categorized by the server. Verify the address format and ensure it meets the required syntax. | - |
| Enhanced Mail System Status Codes | X.1.1 | Bad destination mailbox address | The destination mailbox address is invalid or does not exist. Check for any typos or errors in the recipient's email address. | - |
| Enhanced Mail System Status Codes | X.2.0 | Bad destination system address | The destination system address is invalid or does not exist. Verify the system address and ensure it is correct. | - |
| Enhanced Mail System Status Codes | X.1.3 | Bad destination mailbox address syntax | The syntax of the destination mailbox address is incorrect. Check for any formatting errors or invalid characters in the email address. | - |
| Enhanced Mail System Status Codes | X.1.4 | Destination mailbox address ambiguous | The destination mailbox address is ambiguous or could refer to multiple recipients. Provide a more specific or unique recipient address. | - |
| Enhanced Mail System Status Codes | X.1.5 | Destination mailbox address valid | The destination mailbox address is valid and accepted. No further action is required. | - |
| Enhanced Mail System Status Codes | X.1.6 | Mailbox has moved | The recipient's mailbox has been moved to a different location. Update the address with the new mailbox location. | - |
| Enhanced Mail System Status Codes | X.1.7 | Bad sender鈥檚 mailbox address syntax | The syntax of the sender's mailbox address is incorrect. Check for any formatting errors or invalid characters in the sender's email address. | - |
| Enhanced Mail System Status Codes | X.1.8 | Bad sender鈥檚 system address | The sender's system address is invalid or does not exist. Verify the system address and ensure it is correct. | - |
| Enhanced Mail System Status Codes | X.1.9 | Message relayed to non-compliant mailer | The message has been relayed to a non-compliant mailer. Contact the mailer administrator for further assistance. | - |
| Enhanced Mail System Status Codes | X.2.0 | Other or undefined mailbox status | The specific mailbox status is unknown or not categorized by the server. Check for any additional error details or consult the relevant RFC document. | - |
| Enhanced Mail System Status Codes | X.2.1 | Mailbox disabled, not accepting messages | The recipient's mailbox is disabled and not currently accepting messages. Contact the recipient or their system administrator for further assistance. | - |
| Enhanced Mail System Status Codes | X.2.2 | Mailbox full | The recipient's mailbox is full and cannot receive any new messages. Advise the recipient to clear space in their mailbox or contact their system administrator for increased storage capacity. | - |
| Enhanced Mail System Status Codes | X.2.3 | Message length exceeds administrative limit | The message size exceeds the administrative limit set by the recipient's system. Reduce the message size or contact the recipient or their system administrator for guidance on handling larger messages. | - |
| Enhanced Mail System Status Codes | X.2.4 | Mailing list expansion problem | An issue occurred during the expansion of a mailing list. Verify the validity of the mailing list and its recipients. Contact the list administrator if the problem persists. | - |
| Enhanced Mail System Status Codes | X.3.0 | Other or undefined mail system status | The specific mail system status is unknown or not categorized by the server. Check for any additional error details or consult the relevant RFC document. | - |
| Enhanced Mail System Status Codes | X.3.1 | Mail system full | The mail system's storage capacity has been reached or exceeded. Contact the system administrator for increased storage capacity or advise the sender to resend the message at a later time. | - |
| Enhanced Mail System Status Codes | X.3.2 | System not accepting network messages | The mail system is currently not accepting network messages. Verify the system's availability or contact the system administrator for further assistance. | - |
| Enhanced Mail System Status Codes | X.3.3 | System not capable of selected features | The mail system does not support the selected features required for message delivery. Review the message content or configuration and make necessary adjustments. | - |
| Enhanced Mail System Status Codes | X.3.4 | Message too big for system | The message size exceeds the system's maximum message size limit. Reduce the message size or contact the system administrator for guidance on handling larger messages. | - |
| Enhanced Mail System Status Codes | X.3.5 | System incorrectly configured | The mail system is configured incorrectly, causing issues with message delivery. Contact the system administrator to rectify the configuration problems. | - |
| Enhanced Mail System Status Codes | X.4.0 | Other or undefined network or routing status | The specific network or routing status is unknown or not categorized by the server. Check for any additional error details or consult the relevant RFC document. | - |
| Enhanced Mail System Status Codes | X.4.1 | No answer from host | The mail server could not establish a connection with the destination host. Verify the host's availability and check network connectivity. | - |
| Enhanced Mail System Status Codes | X.4.2 | Bad connection | The connection between mail servers is experiencing issues or is not functioning correctly. Review network connectivity and resolve any connection problems. | - |
| Enhanced Mail System Status Codes | X.4.3 | Routing server failure | A routing server encountered an error or failed during message delivery. Verify the routing configuration and consult the system administrator if the issue persists. | - |
| Enhanced Mail System Status Codes | X.4.4 | Unable to route | The mail server is unable to route the message to the destination. Check the recipient's address and ensure proper routing configuration at the server. | - |
| Enhanced Mail System Status Codes | X.4.5 | Network congestion | The network is congested, leading to delays or issues in message delivery. Retry sending the message after some time or during non-peak hours. | - |
| Enhanced Mail System Status Codes | X.4.6 | Routing loop detected | A routing loop has been detected, causing repeated message delivery attempts within a loop. Review the routing configuration to eliminate the loop and ensure proper message flow. | - |
| Enhanced Mail System Status Codes | X.4.7 | Delivery time expired | The message delivery time has exceeded the specified limit. Resend the message or contact the system administrator for further assistance. | - |
| Enhanced Mail System Status Codes | X.5.0 | Other or undefined protocol status | The specific protocol status is unknown or not categorized by the server. Check for any additional error details or consult the relevant RFC document. | - |
| Enhanced Mail System Status Codes | X.5.1 | Invalid command | The command issued by the sender is invalid or not recognized by the server. Verify the command syntax and resend the message with a valid command. | - |
| Enhanced Mail System Status Codes | X.5.2 | Syntax error | The syntax of the command or request is incorrect. Review the command syntax and ensure it adheres to the protocol standards. | - |
| Enhanced Mail System Status Codes | X.5.3 | Too many recipients | The message has too many recipients, exceeding the recipient limit set by the server. Reduce the number of recipients or split the message into multiple parts. | - |
| Enhanced Mail System Status Codes | X.5.4 | Invalid command arguments | The arguments provided with the command are invalid or not accepted by the server. Check the command syntax and ensure the arguments are valid. | - |
| Enhanced Mail System Status Codes | X.5.5 | Wrong protocol version | The version of the protocol used is incorrect or incompatible with the server. Upgrade or use the appropriate protocol version supported by the server. | - |
| Enhanced Mail System Status Codes | X.5.6 | Authentication Exchange line is too long | The line containing the authentication exchange is too long, exceeding the server's limit. Shorten the line or split it into multiple lines to resolve the issue. | - |
| Enhanced Mail System Status Codes | X.6.0 | Other or undefined media error/bad content | An error related to media or content is encountered, but the specific cause is undefined or unknown. Refer to additional error details or consult the relevant RFC document. | - |
| Enhanced Mail System Status Codes | X.6.1 | Media not supported | The requested media or content is not supported by the mail system. Check the media type or format and ensure compatibility with the server's supported formats. | - |
| Enhanced Mail System Status Codes | X.6.2 | Conversion required and prohibited/bad domain or alias | Conversion of the message or content is necessary, but the conversion is prohibited due to policy restrictions or issues with the domain or alias. Review the conversion requirements and ensure compliance with the server's policies. | - |
| Enhanced Mail System Status Codes | X.6.3 | Conversion required but not supported | The message or content requires conversion, but the server does not support the required conversion method. Check the conversion requirements and ensure compatibility with the server's supported conversion methods. | - |
| Enhanced Mail System Status Codes | X.6.4 | Conversion with loss performed | The message or content has undergone conversion, but some data loss occurred during the process. Consider reviewing the conversion method to minimize data loss or ensure compatibility with the server's conversion capabilities. | - |
| Enhanced Mail System Status Codes | X.6.5 | Conversion failed | The conversion of the message or content has failed due to an error or unsupported conversion method. Verify the conversion settings and ensure compatibility with the server's conversion capabilities. | - |
| Enhanced Mail System Status Codes | X.6.6 | Message content not available | The content of the message is not available or inaccessible. Check the message content availability and ensure proper access permissions. | - |
| Enhanced Mail System Status Codes | X.7.0 | Other or undefined security status/authentication failure/violating site policy | The specific security status or authentication failure is unknown or not categorized by the server. Refer to additional error details or consult the relevant RFC document. | - |
| Enhanced Mail System Status Codes | X.7.1 | Delivery not authorized, message refused | The delivery of the message is not authorized, and it is refused by the server. Check the authorization settings and ensure compliance with the server's policies. | - |
| Enhanced Mail System Status Codes | X.7.2 | Mailing list expansion prohibited | The expansion of mailing lists is prohibited by the server. Review the mailing list expansion policies and ensure compliance with the server's restrictions. | - |
| Enhanced Mail System Status Codes | X.7.3 | Security conversion required but not possible | Security conversion of the message or content is required, but it is not possible to perform the conversion. Check the security conversion requirements and ensure compatibility with the server's capabilities. | - |
| Enhanced Mail System Status Codes | X.7.4 | Security features not supported | The requested security features are not supported by the mail system. Verify the required security features and ensure compatibility with the server's supported security mechanisms. | - |
| Enhanced Mail System Status Codes | X.7.5 | Cryptographic failure | A failure related to cryptographic operations or mechanisms has occurred. Review the cryptographic settings and ensure proper configuration for secure communication. | - |
| Enhanced Mail System Status Codes | X.7.6 | Cryptographic algorithm not supported | The requested cryptographic algorithm is not supported by the mail system. Check the algorithm requirements and ensure compatibility with the server's supported cryptographic algorithms. | - |
| Enhanced Mail System Status Codes | X.7.7 | Message integrity failure | The integrity of the message has been compromised or failed verification. Review the message integrity settings and ensure proper measures for maintaining message integrity. | - |
| Enhanced Mail System Status Codes | X.7.8 | Trust relationship required/Authentication credentials invalid | A trust relationship or valid authentication credentials are required for the message delivery. Verify the trust relationship or authentication credentials and ensure they are valid and properly configured. | - |
| Enhanced Mail System Status Codes | X.7.9 | Authentication mechanism is too weak | The authentication mechanism used is considered too weak or insufficient. Upgrade the authentication mechanism to a stronger and more secure option supported by the mail system. | - |
| Enhanced Mail System Status Codes | X.7.10 | Encryption Needed | Encryption is required for the requested operation or communication. Enable encryption to ensure secure transmission of the message or data. | - |
| Enhanced Mail System Status Codes | X.7.11 | Encryption required for requested authentication mechanism | Encryption is required for the requested authentication mechanism. Enable encryption to fulfill the authentication requirements. | - |
| Enhanced Mail System Status Codes | X.7.12 | A password transition is needed | A password transition is required for the user's account. Follow the provided instructions or contact the relevant administrator to complete the password transition. | - |
| Enhanced Mail System Status Codes | X.7.13 | User Account Disabled | The user account associated with the message is disabled. Enable the user account or contact the relevant administrator to resolve the account status issue. | - |
| Enhanced Mail System Status Codes | X.7.14 | Trust relationship required | A trust relationship is required for the requested operation or communication. Establish the necessary trust relationship to proceed with the operation or communication. | - |
| Enhanced Mail System Status Codes | X.7.15 | Authentication credentials invalid | The provided authentication credentials are invalid or incorrect. Verify the credentials and ensure they are entered accurately. | - |
| Enhanced Mail System Status Codes | X.7.16 | Future release per-user message quota exceeded | The per-user message quota for future releases has been exceeded. Manage the user's message quota or allocate additional storage space to accommodate future messages. | - |
| Enhanced Mail System Status Codes | X.7.17 | Future release system message quota exceeded | The system message quota for future releases has been exceeded. Adjust the system message quota or allocate additional storage space to accommodate future messages. | - |
| Other Errors | 0x0004b9 | - | - | - |
| Other Errors | 0x000501 | - | - | - |
| Other Errors | 0x80000003 | - | - | - |
| Other Errors | 0x80004001 | Not implemented | - | - |
| Other Errors | 0x80004005 | The operation failed | Virus scanner integration issue usually related to script blocking. | - |
| Other Errors | 0x800300FD | Unknown Error | Indicates that there is insufficient space in the Temp folder.<br>- Empty your Deleted Items folder<br>- Empty your Temp folder: C:\Windows\Temp | - |
| Other Errors | 0x80040109 | The Operation cannot be performed because the message has been changed | Virus scanner integration issue. Some add-in may have altered the message upon sending. | - |
| Other Errors | 0x8004010F | Microsoft Exchange offline address book. Not downloading Offline address book files. A server (URL) could not be located. | Verify the publication address for the Offline Address Book (OAB) in Exchange. | - |
| Other Errors | 0x80040115 | The connection to the Microsoft Exchange server is unavailable. Outlook must be online or connected to complete this action. | The server is not reachable, check your connection and verify that Outlook is in online mode. This issue could also occur with other mail servers, not just Exchange. | - |
| Other Errors | 0x80040119 | An unknown error has occurred. Messaging interface has caused an unknown error. | Virus scanner integration issue usually related to authentication. This issue could also occur when there are errors in your PST file. | - |
| Other Errors | 0x8004011D | Task "Microsoft Exchange Server" reported error (0x8004011D): "The server is not available. Contact your administrator if this condition persists." | The server is not reachable, check your connection and verify that Outlook is in online mode. This issue could also occur with other mail servers, not just Exchange. | - |
| Other Errors | 0x80040126 | The operation cannot be performed because the connection to the server is offline. | This issue is an Outlook Connector issue. If there are no general issues with Hotmail itself, make sure you have the latest version installed. Removing and re-adding your Hotmail account might help. | - |
| Other Errors | 0x80040305 | Your server administrator has limited the number of items you can open simultaneously. Email too big (Google Apps Sync) | These limitations can be set on the mail server. Contact your mail admin to find out which limitations are in effect. | - |
| Other Errors | 0x80040600 | An unknown error has occurred. | Virus scanner integration issue usually related to authentication. This issue could also occur when there are errors in your PST file. | - |
| Other Errors | 0x80040607 | An unknown error occurred | Virus scanner integration issue. Authentication not enabled for the configured SMTP server. | - |
| Other Errors | 0x8004060C | Unknown Error | - | - |
| Other Errors | 0x80040900 | - | - | - |
| Other Errors | 0x80040FB3 | Error encountered. Check documentation. | This issue is related to BlackBerry accounts. It appears that your account is not associated with a BES or Exchange account. Other causes could be a corrupted item that is trying to be synced. Remove this item and try again. | - |
| Other Errors | 0x80042108 | Outlook is unable to connect to your incoming (POP) e-mail server. If you continue to receive this message, contact your server administrator or ISP. | - | - |
| Other Errors | 0x80042109 | Outlook cannot connect to your outgoing (SMTP) e-mail server. If you continue to receive this message, contact your server administrator or ISP. | - | - |
| Other Errors | 0x8004210A | The operation timed out waiting for a response from the receiving (POP) server. If you continue to receive this message, contact your server administrator or ISP. | Virus scanner integration issue. | - |
| - | 0x8004210B | The operation timed out waiting for a response from the sending (SMTP) server. If you continue to receive this message, contact your server administrator or ISP. An address in the distribution list might be malformed or corrupted. Update/remove the address or recreate the distribution list. | Other Errors | |
| Other Errors | 0x80042112 | - | - | - |
| Other Errors | 0x8004218 | - | - | - |
| Other Errors | 0x80048002 | This task was canceled before it was completed. | Virus scanner integration issue. Some add-in may have altered the message upon sending. | - |
| Other Errors | 0x8004DF0B | - | - | - |
| Other Errors | 0x80070005 | You don't have appropriate permissions to perform this operation | Refers to issues with the delivery location:<br>- Scan it for errors with scanpst.exe or scanost.exe<br>- Verify that you have read/write permissions on the PST/OST file<br>- Verify that the path to the PST/OST file is valid<br>- Verify that the OST file belongs to the correct user and mailbox | - |
| Other Errors | 0x8007000E | - | - | - |
| Other Errors | 0x80070021 | - | - | - |
| Other Errors | 0x80070057 | Could not complete operation. One or more parameter values are not valid. Sending reported error parameters not correct. | Virus scanner integration issue. This error could also occur with Google Apps Sync trying to sync your RSS folders to the server. | - |
| Other Errors | 0x80072F17 | Synchronization could not be completed. Try again later. | This issue is usually caused by issues with the SSL certificate. | - |
| Other Errors | 0x8007007E | Unknown error | - | - |
| Other Errors | 0x80090FB3 | - | - | - |
| Other Errors | 0x800C0131 | Unknown error has occurred. | Data storage issue | - |
| Other Errors | 0x800C0133 | Unknown error has occurred. | Data storage issue. Virus scanner integration issue. | - |
| Other Errors | 0x800C013B | - | - | - |
| Other Errors | 0x800CCC33 | Task 'Hotmail: Folder:Inbox Synchronizing headers.' reported error (0x800CCC33): 'Access to the account was denied. Verify that your username and password are correct. The server responded 'Forbidden'.' | This error is encountered when you are trying to make a connection to a Live Hotmail account without the Outlook Connector installed. | - |
| Other Errors | 0x800CCC7D | Unknown Error | The outgoing SMTP server does not support secure connections. Verify your account settings or contact your ISP. | - |
| Other Errors | 0x800CCC80 | None of the authentication methods supported by this client are supported by your server. | - | - |
| Other Errors | 0x800CCCF7 | - | - | - |
| Other Errors | 0x81FC0005 | - | Close and reopen Outlook | - |
| Other Errors | 0x834005 | - | - | - |
| Other Errors | 0xC0000005 | - | - | - |
| Other Errors | 0xD4904005 | - | - | - |
Sendgrid
| Error | Message | Explanation | Troubleshooting | Glossary |
| 250 | Queued mail for delivery | Your mail has been successfully queued! This response indicates that the recipient server has accepted the message. | - | - |
| 403 | You are not authorized to send from that email address | This means the "from" address does not match a verified Sender Identity. Mail cannot be sent until this error is resolved. To learn how to resolve this error, see our Sender Identity requirements. | Verify the Sender Identity configuration and ensure that the "from" address is correctly set. | Sender Identity: A verified email address or domain that is authorized to send emails from a specific sender. |
| 421 | Message from (X.X.X.X) temporarily deferred | Messages are temporarily deferred because of recipient server policy - often it's because of too many messages or connections in too short of a timeframe. We continue to retry deferred messages for up to 72 hours. Consider temporarily sending fewer messages to a domain that is returning this code because this could further delay your messages currently being tried. | Reduce the frequency or volume of messages being sent to the recipient domain. | Deferred: A temporary delay in the delivery of a message. |
| 450 | too frequent connects from 198.37.147.135, please try again later. | The message failed because the recipient's mailbox was unavailable, perhaps because it was locked or was not routable at the time. We continue to retry messages for up to 72 hours. Consider temporarily sending fewer messages to a domain that is returning this code because this could further delay your messages currently being tried. | Wait and allow the recipient's mailbox to become available again. | Mailbox Unavailable: The recipient's mailbox is not currently accessible or cannot accept incoming messages. |
| 451 | Temporary local problem - please try later | The message simply failed, usually due to a far-end server error. We continue to retry messages for up to 72 hours. | Retry sending the message after some time. | Temporary Server Error: A temporary issue or error on the recipient server that prevented the successful delivery of the message. |
| 451 | Authentication failed: Maximum credits exceeded | There is a credit limit of emails per day enforced in error. Contact support to remove that limit. | Contact support to resolve the credit limit issue. | Authentication: The process of verifying the identity of the sender or recipient of an email to ensure secure communication. |
| 452 | Too many recipients received this hour (throttled) | The message has been deferred due to insufficient system storage. We continue to retry messages for up to 72 hours. | Reduce the number of recipients in the message or split the message into multiple smaller messages. | Throttling: Limiting the number of messages or connections allowed within a specific timeframe to manage system resources and prevent abuse. |
| 550 | Requested action not taken: mailbox unavailable | The user鈥檚 mailbox was unavailable. Usually because it could not be found or because of incoming policy reasons. Remove these addresses from your list - it is likely fake, or it was mistyped. | Verify the recipient's email address and remove any invalid or mistyped addresses from the list. | Mailbox Unavailable: The recipient's mailbox is not accessible or does not exist. |
| 550 | You are temporarily blocked from sending emails due to repeated bad requests. | Too many bad requests, such as bad sender or bad recipient address, have been sent in a short timeframe. A temporary block of a few minutes has been activated to prevent more bad requests until a fix can be implemented. | Wait for the temporary block to be lifted and ensure that future requests adhere to the correct format and guidelines. | Bad Requests: Invalid or incorrect requests sent to the recipient server. |
| 551 | User does not exist. | The intended mailbox does not exist on this recipient server. Remove these addresses from your list. | Verify the recipient's email address and remove any addresses that do not exist. | Invalid Recipient: An email address that does not exist or is not recognized by the recipient server. |
| 552 | This message is larger than the current system limit or the recipient鈥檚 mailbox is full. Create a shorter message body or remove attachments and try sending it again. | The recipient's mailbox has exceeded its storage limits. We don't resend messages with this error code because this is usually a sign that this is an abandoned email. | Reduce the size of the message by removing attachments or shortening the message body. | Mailbox Full: The recipient's mailbox has reached its storage capacity and cannot accept additional messages. |
| 553 | Invalid/inactive user. | The message was refused because the mailbox name is either malformed or does not exist. Remove these addresses from your list. | Verify the recipient's email address and remove any invalid or inactive addresses from the list. | Invalid User: An email address that is either formatted incorrectly or does not exist on the recipient server. |
| 554 | ERROR: Mail refused | This is a default response that can be caused by a lot of issues. There is often a human-readable portion of this error that gives more detailed information, but if not, remove these addresses from your list. | Review the specific error message provided, if available, and take appropriate action based on the details. Remove any invalid or problematic addresses from the list. | Mail Refused: The recipient server refused to accept or deliver the message for various reasons. |
| Other | Delayed Bounce - Unable to Parse Server Reason | This is what SendGrid displays when the recipient's server returns a blank reason code. | - | - |
| Turning off click tracking | - | To turn off click tracking, add this to your X-SMTPAPI header: {"filters": {"clicktrack": {"settings": {"enable": 0}}}} | Update the X-SMTPAPI header in your email sending code to disable click tracking. | Click Tracking: A feature that tracks and records when recipients click on links within an email message. |
| Invalid SMTP API header | - | When you try to send an invalid X-SMTPAPI header, you will get an email with details about the invalidations. You may also see errors on your Email Activity page or in your Event Webhook data. If this happens, the email should give you the information you need to begin troubleshooting. We also recommend uploading your JSON into a JSON validator because this is often an invalid JSON issue. | Review the email received with details about the invalid header and use the information provided to troubleshoot and correct the issue. Ensure that the X-SMTPAPI header is properly formatted and contains valid JSON. | SMTP API Header: An additional header included in the email to provide instructions and customization options for SendGrid's services. |
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