Why do remote servers continually attempt to send mail to full mailboxes?

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One of the users on my system has allowed their mailbox to become full. This has resulted in mail for that user being rejected, but the remote servers continue to atempt to send the message resulting in a great increase in traffic between these two servers.


GMS supports the ESMTP size extension by default. If the sending server also supports this then the size of the message is transmitted as part of the protocol exchange and little bandwidth is used in processing messages that will exceed the users mailbox limits. However not all mail servers support this ESMTP extension, and in those cases the complete message must be transferred before the actual size of the message can be calculated.

By default GMS rejects messages that will cause the size of the users mailbox to be exceeded with a 431 SMTP error code. This indicates a temporary failure and is used to prevent any legitimate mail from being lost because the owner of the account may download the email and clear it out.

The sending server will attempt to resend the message at whatever frequency it is set to retry messages at. This is normally set around 10 minutes but every server is different, the default within GMS is 12 minutes.

There are a number of options open to you to stop the remote server continually retrying the message.

  • The preferable option is to contact the user in question and ask them to reduce the size of their mailbox so that the message will be accepted.
  • If there is a lot of old messages in the mailbox you could purge these using the automatic purging facilities available under Mail > Domains > Purge Email, but this will affect all users on the system.
  • Change the SMTP response returned by GMS to a permanent failure. To do this go to Profiles > System Base Profile > Account, select the option "Permanently reject email" and click on the Update button. Note that this will permanently reject mail for all users in this situation.

See Also:

Keywords:full mailbox bandwidth continual sending

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