Hello, I followed several times this perfect server article and I still am unable to send emails. My setup: Test Ubuntu server hosted on my machine using Vmware. The domain I'm trying to use is domain.com and I have entries to hosts file that points it to this server. After finishing the guide everything works fine, apart from being able to send emails within the same domain, example from [email protected] to [email protected] - both mailboxes created and passwords are correct. mailq gives the following: Code: 73F16602A2 565 Fri May 20 10:26:50 [email protected] (host 127.0.0.1[127.0.0.1] said: 451 4.5.0 id=01721-01 - Temporary MTA failure on relaying, From MTA() during fwd-connect (All attempts (1) failed connecting to smtp:127.0.0.1:*): id=01721-01 (in reply to end of DATA command)) [email protected] I tried removing AV, also increased the memory size of the machine, no luck.