I've been struggling with this for a bit now. I've just migrated the last few people over to Zimbra and I'm ready to kill my old host. The problem is that the Zimbra server insists on relaying still.

I had my old host set to the zimbraMtaRelayHost variable, which worked fine. Earlier today I cleared it out and the value is now blank, as checked by
"zmlocalconfig |grep zimbraMtaRelayHost" which returns nothing. I've restarted the server several times today for various reasons, but still when I look at the main.cf file it shows

relayhost = oldhost.domain.com

Shouldn't that file regenerate on server restart? If not, what special command should I be running?