On Wed, Aug 18, 2010 at 9:38 AM, George Njoroge <themburu@gmail.com> wrote:

Hey guys,

I would like to set up a mail server that should be quite easy to scale.

I initially had Sendmail in mind but upon some digging guys out there opt for Postfix or even better QMail.

Ati, "even better, Qmail"? My friend, QMail is dead!

I need to know which is the best MTA application to use for factors like security management, spam handling, capacity handling, server resource utilization, management etc and can you incoorperate multiple accounts on different domains?

Exim or Postfix will do. Postfix beats Exim in queue processing (only!). Exim configuration language is so flexible that the moment you understand it, you can typically do anything under the sun!
I'm biased towards Exim any time.

Talking of management, I wonder what you mean.

Multiple accounts on different domain is also called "virtual domains" and that is supported by both, using flat files, DBs like MySQL, PostgreSQL, Oracle, OpenLDAP, sqlite...

Capacity handling and resource utilization depends on how you "tune" your server (disk speeds, RAM) and the SMTP engine.