[phoenix]

Originally Posted by sgatto

I've tested smtp authentication with Email Server Test - Online SMTP diagnostics tool. Seems like zimbra accepts rcpt to without asking for authentication.

Of course it accepts the connection without authentication, that's what mail servers do on port 25 - they accept connections from other mail servers and do not need authentication for that.

Originally Posted by sgatto

What's wrong with this ? Is a nat problem ? Or is that service not reliable ?

Nothing is wrong with that, the output from that test should also show the 'Relay access is denied'. Zimbra is not, by default, an open relay unless you've made it one.