Unable to send/receive emails on a Plesk server: Message size exceeds server limit

Symptoms

• When sending an email in webmail, the operation fails with the following error message:

  PLESK_INFO: SMTP Error: Message size exceeds server limit

• Emails with large attachments (more than 10 MB) are not received. The sender receives the following email message about failed email delivery:

  PLESK_INFO: 552 5.3.4 Message size exceeds fixed limit

• The following error message may appear in /var/log/maillog:

  CONFIG_TEXT: warning: queue file size limit exceeded

Cause

The size of the email exceeds the limit configured in Plesk at Tools & Settings > Mail Server Settings > Maximum message size.

Note: When adding an attachment, its size is automatically increased due to the encoding that is performed when forwarding an email. On average, the email is enlarged by approximately 35-40% of the original attachment size. For instance, if you set a limit of 10 MB and send an email with a 9 MB attachment, the email will be rejected.

Resolution