Install Qmail on a Fresh Centos Server
Installing Qmail/Vpopmail on Centos 6 Server
Do you want to setup a mail server quick? or the default Centos 6 mail server (postfix/sendmail) not working correctly for you. One of the best MTA out there to date is Qmail.
Qmail is a mail transfer agent (MTA) that runs on Unix. It was written, starting December 1995, by Daniel J. Bernstein as a more secure replacement for the popular Sendmail program. qmail's source code is in the public domain.