Build a Mail Server with Commodity Hardware and FreeBSD, Part 2 (the Extras)

In Part 1of this TechBuilder Recipe, I showed you how to create a secure, basic e-mail server for your SMB customers by using open source software, specifically FreeBSD, Postfix, and Dovecot. Now in Part 2, you'll learn how to extend the functionality of that basic system by adding virus protection, spam detection, and Webmail access.

The system we built in Part 1 of this Recipe used only free, open-source software. Same with Part 2. All the programs you'll need are free, open-source software. They are all included in the FreeBSD ports and packages system, as discussed in Part 1.

Today, any mail server that lacks protection again spam and viruses is considered incomplete. To provide these functions, I recommend the following freeware:

• amavisd-new, a high-performance interface between mailer and content checkers, will serve as your content filter.
• ClamAV, short for Clam Anti-Virus, will filter out viruses.
• SpamAssassin, an open-source spam filter from the Apache Project, will filter out junk e-mail. (Amavisd-new is a Perl script and actually integrates SpamAssassin, which will save time and effort.)

In this Recipe, I will instruct you to install both the ClamAV and amavisd-new packages from the FreeBSD packages system. So you won't need to manually download them. Also, since SpamAssassin is part of amavisd-new, you won't need to download that separately, either.

Most mail servers now let users send and receive e-mail by using a Webmail interface through a browser-- not just by using a client like Outlook or Eudora. One of the best Webmail packages available is SquirrelMail, a standards-based package written in PHP4. It which renders pages in pure HTML 4.0 with no requirement for Javascript.

As I did in Part 1 of this Recipe, I'll use

Courier font

for highlighting commands or filenames, and a percentage sign (%) to represent the command prompt. I'll also continue installing applications using the pre-compiled packages system.

You may remember from Part 1 that we installed our base system from a CD. Assuming your system has Internet access, changing your installation source to one of the FreeBSD FTP mirror servers will let you add packages without needing to swap CD discs. This is extremely handy when working remotely.