I have seen that PLESK is using the virtual alias table in /var/spool/postfix/plesk to tell postfix which alias to use when sending an email.
If the E-Mail service for a domain is deactivated all of the aliases of this deactivated domain are still kept in the virtual.db file. This leads to mails which cannot be delivered, because the alias which is used is unknown on the (external) destination host.
I think this is a bug in PLESK, because PLESK is doing the configuration of the virtual.db file.
As a workaround I removed the virtual file in the following configuration line:
Original: virtual_alias_maps = hash:/etc/postfix/virtual, hash:/var/spool/postfix/plesk/virtual
Now: virtual_alias_maps = hash:/etc/postfix/virtual
Please consider this to be solved for future releases
If the E-Mail service for a domain is deactivated all of the aliases of this deactivated domain are still kept in the virtual.db file. This leads to mails which cannot be delivered, because the alias which is used is unknown on the (external) destination host.
I think this is a bug in PLESK, because PLESK is doing the configuration of the virtual.db file.
As a workaround I removed the virtual file in the following configuration line:
Original: virtual_alias_maps = hash:/etc/postfix/virtual, hash:/var/spool/postfix/plesk/virtual
Now: virtual_alias_maps = hash:/etc/postfix/virtual
Please consider this to be solved for future releases