Librenix has a posted small and sweet article that explains basic steps to configure and install a mail server with antivirus / antispam in minutes.
From the article:
This article illustrates a situation where you need to set up your own mail server (be it your home mail server, or a small office one). It actually shows that, if using an integrated service mail server, anyone can do the job, all in a matter of minutes.
AXIGEN Mail Server, the solution chosen for this example, can send and receive e-mails securely via "mydomain.com" and is able to retrieve them in a WebMail interface - this means that it includes all mail services needed for a fully functional mail server (SMTP, IMAP, POP3, WebMail, WebAdmin).
To get an idea of the amount of time you can spare by installing such a solution, just think of all the different open source applications you would need to install instead (i.e. an MTA, Squirrelmail for Webmail, QmailAdmin for web configuration, Courier for IMAP and POP3 and many others.)