SMTP Response Codes
Facebook provides Enhanced Mail System Status Codes as described in
RFC 1893. Facebook also provides custom error codes to help system administrators troubleshoot delivery issues.
Facebook System Resource Issues
These codes indicate a temporary issue internal to Facebook's system. Administrators observing these issues are not required to take any action to correct them.
INT-T1
INT-T2
INT-T3
INT-T4
INT-T5
INT-T6
INT-T7
INT-T8
INT-T9
INT-T10
INT-T11
INT-T12
Sender Domain Issues
These codes indicate an issue with either your domain's DNS record or your mail server's reverse DNS record.
Permanent IssuesThese will persist until action is taken to correct them.
DNS-P1 Your SMTP MAIL FROM domain does not exist.
DNS-P2 Your SMTP MAIL FROM domain does not have an MX record.
DNS-P3 Your mail server does not have a reverse DNS record.
Temporary Issues These may only persist for a short time. Administrators may want to investigate them further if they occur often.
Recipient Issues
These codes indicate an issue with one of the message recipients. Administrators observing these issues are not required to take any action to correct them.
RCP-P1 The attempted recipient address does not exist.
RCP-P2 The attempted recipient's preferences prevent messages from being delivered.
RCP-T1 The attempted recipient address is not currently available due to an internal system issue. This is a temporary condition.
INT-P1 The attempted recipient address does not exist.
INT-P3 The attempted recpient group address does not exist.
INT-P4 The attempted recipient address does not exist.
Message Issues
These codes indicate an issue with the specific message that triggered them. Message authors observing these issues are required to take action to correct them.
MSG-P1 The message exceeds Facebook's maximum allowed size.
INT-P2 The message exceeds Facebook's maximum allowed size.
MSG-P2 The message contains an attachment type that Facebook does not accept.
MSG-P3 The message contains multiple instances of a header field that can only be present once. Please see
RFC 5322, section 3.6 for more information.
MSG-T1 The number of recipients on the message exceeds Facebook's allowed maximum.
Connection Limits
These codes indicate an issue with the connections from your mail servers. They are temporary conditions and administrators observing them are not required to take any action to correct them.
CON-T1 Facebook's mail server currently has too many connections open to allow another one.
CON-T2 Your mail server currently has too many connections open to Facebook's mail servers.
CON-T3 Your mail server has opened too many new connections to Facebook's mail servers in a short period of time.
CON-T4 Your mail server has exceeded the maximum number of recipients for its current connection.
Policy Violations
These codes indicate that either the message or your mail server has violated Facebook's abuse prevention policies.
Permanent Mail Server Policies These will persist until the administrator takes action to correct them.
Permanent Message Policies Message authors observing these issues are required to take action to correct them.
POL-P5 The message contains a virus.
POL-P6 The message contains a url that has been blocked by Facebook.
POL-P8 The message does not comply with Facebook's abuse policies and will not be accepted.
Permanent Domain PoliciesThese will persist until action is taken to correct them.
Temporary Mail Server PoliciesThese will expire after the stated duration. Administrators are encouraged to take corrective action to prevent them from reoccurring.
POL-P3 Facebook is not accepting messages from your mail server. This will persist for 4 to 8 hours.
POL-P4 Facebook is not accepting messages from your mail server. This will persist for 24 to 48 hours.
POL-T1 Facebook is not accepting messages from your mail server, but they may be retried later. This will persist for 1 to 2 hours.
POL-T2 Facebook is not accepting messages from your mail server, but they may be retried later. This will persist for 4 to 8 hours.
POL-T3 Facebook is not accepting messages from your mail server, but they may be retried later. This will persist for 24 to 48 hours.