I've just installed Zimbra on Fedora Core 4 and it seems to be running OK. I'm sending mail via an external smtp, which also seems to be working.
However, I set up a test account and sent an email from that address to itself and it would only work if I addressed it with the FQDN, e.g. sending a message to firstname.lastname@example.org works, sending a message to email@example.com doesn't, I just get a bounce back from the server.
I'm sure there's something simple I'm overlooking but I can't figure it out. Any help gratfully received.