This will be the goto to help solve e-mail delivery issues and talk about many practical issues that happen between developers, admins and scripts that send e-mail and do things that may not be acceptable or cause deliverability problems.
Sendmail Stuff
Edit /etc/mail/sendmail.mc
The problem is that if you send directly out from the server using the mail function, the Return-path of the e-mails will be username@thehostnameoftheserver.com. Let........
Ihave no idea how to get the loopback device working in OpenVZ, but what's more frustrating is that I purchased a CPanel license for my VPS and clearly it is not "VPS Optimized". Although everything does seem to work at this point despite that error.
The suggestions here: http://forum.openvz.org/index.php?t=msg&goto=1339 don't seem to work at all. This is an OpenVZ issue, but also a CPanel isue, why on earth would loopback support be expected in a VPS a........