Oracle Cloud Infrastructure Documentation

Troubleshooting Email Delivery

This topic provides troubleshooting solutions for problems you might encounter using Email Delivery.

TLS errors when integrating with Postfix

  • If you are encountering TLS errors when attempting to integrate Postfix with Email Delivery, ensure that the following setting is removed from the Postfix main.cf file, as it has been deprecated:
  • smtp_use_tls = yes

  • Use the following setting instead to turn on TLS:
  • smtp_tls_security_level = may

    Using this setting, the Postfix SMTP server announces STARTTLS support to remote SMTP clients, but does not require that clients use TLS encryption.

  • If you want to enforce the use of TLS, so that the Postfix SMTP server announces STARTTLS and accepts no mail without TLS encryption, use the following setting:
  • smtp_tls_security_level = encrypt

For more information, see Postfix TLS Support.

Connectivity Issues

Note

Email Delivery does not prohibit connectivity from any source IP range. Any IP that attempts to connect to Email Delivery will be accepted.

Refer to SMTP Connection Endpoints for a list of regional endpoints to establish SMTP connections for sending.

To troubleshoot a problem connecting to endpoint network ports
To troubleshoot a problem connecting to an external mail transfer agent (MTA)

Common Errors Returned by Email Delivery

API Errors

For a complete list of common errors returned by all the services for Oracle Cloud Infrastructure, see API Errors.

Common SMTP Errors Returned by Email Delivery

The following table lists the common errors returned by the Email Delivery SMTP service.

HTTP Status Code Error Code Description
451 Server error An unexpected error has occurred during the SMTP conversation.
451 Error in Processing An unexpected error has occurred during the SMTP conversation.
452 System storage error The server is unable to persist the message in its delivery queue.
455 Maximum messages sent per minute reached : limit is <limit> The SMTP send burst rate (of messages accepted per minute period) has been exceeded.
455 Maximum messages sent per day reached : limit is <limit> The SMTP daily send rate (of messages accepted per 24 hour period) has been exceeded.
471 Authorization failed: address <address> not authorized

Authorization of the address (either in the envelope or message) has failed for the SMTP user.

501 Invalid command argument, not a valid Base64 string

The base64 encoded AUTH (PLAIN) secret is invalid.

501 Invalid command argument, does not contain NUL The base64 encoded AUTH (PLAIN) secret does not contain NUL field separator(s).
501 Invalid command argument, does not contain the second NUL The base64 encoded AUTH (PLAIN) secret does not contain NUL field separator(s).
504 Method not supported The client has attempted to use an unsupported AUTH mechanism with our service.
504 AUTH mechanism mismatch The client has sent an invalid AUTH command to our service.
523 Exceeds byte limit The message has exceeded the size limit enforced by the service (see server response to EHLO for size restriction).
535 Authentication credentials invalid Authentication of the SMTP user has failed.
535 Authentication required The client has sent commands that require SMTP authentication succeeded before the service is able to process (that is, commands are being sent out of order).
553 <address> Invalid email address The RFC-822 Internet Address sent by the client is invalid.
554 Message parse error The RFC-2822 Internet Message is invalid (and unable to be parsed by the server).