Messages with large files in attachment are not checked by SpamAssassin on a Plesk server: skipped message, greater than max message size (256000 bytes)

Symptoms

• Emails with large file in attachment (more than 256 KB) are not checked by SpamAssassin. When such an email is received, the following message appears in /var/log/maillog:

  plesk spamc[28423]: skipped message, greater than max message size (256000 bytes)

• These emails are also ignored by the mailbox-level blacklist.

Cause

By default, SpamAssassin does not check messages with attachments larger than 256KB. This value provides normal server loading. A larger value may cause heavy load on a server when processing large files.

The mailbox-level blacklist is SpamAssassin blacklist. When SpamAssassin ignores emails with large files and does not scan them, it does not check the domain name against its blacklist. Therefore, such messages are delivered.

Resolution

1. Connect to the Plesk server via SSH.

2. Open the file /etc/psa/psa.conf in any text editor. In this example, we are using the vi editor:

   # vi /etc/psa/psa.conf

3. Find the line SpamAssassin max mail size (in bytes) and increase the value of the SA_MAX_MAIL_SIZE parameter.

   Note: The value of SA_MAX_MAIL_SIZE is in bytes. In the example below, SpamAssassin will check all messages with the size up to 768KB:

   # SpamAssassin max mail size (in bytes)
   SA_MAX_MAIL_SIZE 768000

4. Save the changes and close the file.