Mail is forwarded without mail forwarding enabled

Symptoms

• Email messages are forwarded to another mailbox, even though forwarding is disabled in Plesk > Domains > example.com > Mail Addresses > [email protected] > Forwarding tab

• The following is logged to /var/log/maillog when the messages are forwarded:

  sieve: [email protected]: redirect action: forwarded to [email protected]

Cause

There's a forwarding rule configured at the webmail level.

Resolution

1. Log in to the domain's webmail at webmail.example.com

2. Go to Settings > Filters

3. Find the filter responsible for the forwarding. For example:

   

4. Remove or disable the filter