Outbound Mail returned by [e-mail]

Products

• Email Security.cloud

Issue/Introduction

An email sent outbound by one of your users is bounced back by Symantec.Cloud advising that the message could not be delivered.

This is the mail delivery agent at messagelabs.com.

I was unable to deliver your message to the following addresses:

Cause

This error communicate that we accepted the message but we could not deliver it to the intended recipient server. We will include the refusal message that the recipient server provided which is the best source of information regarding the cause of the rejection.  Some examples of issues and corresponding error messages:

• The email was larger than the recipient server will accept:
  • 552 5.3.4 Message size exceeds fixed maximum message size
  • 552 Message size exceeds fixed limit​

• The recipient's mailbox is full:
  • 552 Mailbox is full
  • 552 Requested mail action aborted: exceeded storage allocation​ 

• The recipient address isn't one registered on the recipient server:
  • 550 User unknown
  • 554 5.7.1 Recipient address rejected: No such user​

• The recipient server is not configured to accept mail for the recipient domain:
  • 550 5.7.1 Unable to Relay
  • 554 5.7.1 Relay access denied

• The recipient server finds something suspicious in the message content:
  • 550 5.7.1 Message rejected as spam by Content Filtering.
  • 554 Denied (Mode: normal)
  • 550 Denied by policy
  • 552 MS-Office file containing VBA macros found inside of the email
  • 550 5.7.1 Message rejected due to content restrictions

• The recipient server has an issue with the sending email address:
  • 554 5.1.0 Sender denied
  • 553 Envelope sender rejected

• The sending server cannot be seen as authorized for the sending domain:
  • 550 SPF check failed. Sender not authorized
  • 550 Sender verify failed
  • 550 5.7.1 SPF unauthorized mail is prohibited. 

• There was a temporary issue on the recipient server that was not resolved before the message retry time expired:
  • 554 5.4.7 [internal] exceeded max time without delivery

Resolution

Note that this list is not exhaustive, and server error messages may not exactly match those listed above, although they are often similar.

Most of these issues need to be resolved on the recipient's system, as it is that system rejecting the messages. In some cases, you may need to verify the recipient's email address or modify the message content to prevent it from being blocked by the recipient's server.

If you are uncertain whether the bounce is due to Symantec Email Security.Cloud blocking the email, you can use the Track and Trace feature to locate the specific email and review scanning and delivery details to confirm.

For SPF or sender verification issues, you may need to implement or update your SPF record. For guidance, refer to the KB article Implement SPF records for Email Security.cloud

If you are unable to determine the cause of the message failure, please open a case with Symantec Technical Support. We can assist you in understanding the issue through troubleshooting, analyzing message logs, and providing recommendations to resolve the problem.