If you have all-in-one Zimbra install (all services on one host), you should do a zmcontrol status first, make sure the mta service is running. If you have a multi-server, and MTA services is running elsewhere, check that server (zmcontrol status). You can look in /var/log/zimbra.log on the server where the MTA is running to perhaps get clues. The basic mechanics is the value for zimbraSmtpHostname (observe with zmprov) is where the webmail is attempting to connect when you hit Send if that server is down or blocked you get the message you describe.
Statistics: Posted by karl.b — Fri Apr 05, 2024 9:43 pm