[BUG] PHP mail() sends emails locally even with disabled mail service on domain

Symptoms

• PHP mail() sends emails locally even with disabled mail service on a domain. In /var/log/maillog:

  CONFIG_TEXT: user postfix/qmgr[25694]: 6890A415A5FB: from=[example@example.com], size=377, nrcpt=1 (queue active)
  user postfix/local[26823]: 6890A415A5FB: to=<_plesk_bounce_example.com@localhost.localdomain>, orig_to=<anydomain@example.com>, relay=local, delay=0.01, delays=0/0/0/0.01, dsn=5.2.1, status=bounced (This address no longer accepts mail. )

• Service plan has the following mail settings for subscriptions in Service Plans > Service Plan name > Mail:

• Mail service is disabled

• Bounce with the message emails to non-existent mailboxes

• Alias to bounce messages preserved in virtual_alias_maps:

  # postmap -s /var/spool/postfix/plesk/virtual | grep _plesk_bounce
  @example.com _plesk_bounce_example.com@localhost.localdomain

Cause

This issue is considered as the Plesk bug #PPPM-8893, which is going to be fixed in the future updates.

Resolution

Until the fix becomes available, one of the workarounds may be used:

1. Log into Plesk;

2. Switch mail service for domains on/off in Domains > example.com > Mail Settings > Activate mail service on this domain.

OR

1. Connect to the server via SSH;

2. Use the command line utility:

   # plesk bin mail --on example.com

   # plesk bin mail --off example.com