I am setting up a zimbra server in hopes of weaning myself off of my upstream host owner's technical support. So far I am only partially successful.
As I am a residential Comcast subscriber, and they mistakenly believe that only spammers would want a home mail server, they block several well-known ports.
I have successfully configured outbound email (see MTAServerSettingsLow.jpg) to go to a nontraditional port (8088), and mail from my webclient account delivers just fine.
I am unable to get inbound trafic to work. (see TheError.jpg). I configured the upstream IP (18.104.22.168/32) into the MTA trusted networks, and later turned off DNS lookups, but I still fail.
Any assistance will be greatly appreciated. If I need to dump a configuration to help you help me, please point me to the appropriate place. I'm trying to stay within the GUI to get things configured, as that was a primary goal in my administration simplification choice.