I've noticed this on a few servers so unless I'm misunderstanding something I think it's been a bug for awhile. Under Options >> Mailserver you can set it to External Mailserver but the domain is never removed from /etc/postfix/local-host-names. It also re-appears next time you edit a site if removed manually. Can anyone else confirm this or am I misunderstanding what this option is supposed to do?
Let'S assume you have a web site www.example.com with the Co-Domain example.com. If you go to the Options tab and set the mailserver to external, then www.example.com will be removed from local-host-names, but example.com won't. For example.com, you must go to the Co-Domains tab, select example.com, go to the Options tab and set example.com to "External MAilserver" as well.
