Follow step 1 through 5 before installing all of these packages!
Install Exim package. You have to make sure that no other smtp or pop/imap server is running on your computer. Remove the following file from the "LaunchDaemons" folder '/System/Library/LaunchDaemons/org.postfix.master.plist'.
(Exim is based on this build instructions)
Install the Courier Package.
DO NOT create directories for user accounts and/or domains inside mail folder. They will be created automatically upon the arrival of the first email sent to the users, listed in the mysql setup.
(Courier is based on this build instructions)
Download and unpack mailAdmin.tgz package. Open "connection.inc.php" and edit the "$connection" line with your database username and password. It also contains a file called "email_db.sql" - move it to your home (root) directory. Move the rest of the folder to wherever you serve files via apache.
Open terminal, login as root. (I assume you do have some familiarity with MySql)
mysql -u root -p mysql> CREATE database email_db; mysql> use email_db; mysql> \. /private/var/root/email_db.sql mysql> quit
Test it by pointing your browser to http://www.yourdomain.com/mailAdmin/. If you're able to add or delete records to all four categories then proceed to step 4.
You're going to need Apple Developer Tools (Xcode). Comes with both Tiger Client and Server, so all you have to do is just install it.
(Login as "root") If this is a new Tiger installation, you'll have to initialize perl and install a few modules before you can install SpamAssassin:
sudo cpan install Bundle::CPAN install HTML::Parser install Net::DNS quit
Install DBI_1.48 and DBD_Mysql-3.0002 packages (or build yourself) before you continue installing SpamAssassin via terminal.
sudo cpan install Mail::SpamAssassin quit
Download and install SpamAssassin start up and config files. (Link above)
Install ClamAV packages. ClamAV requires that you install GMP (GMP 4.1.4 link above).
(ClamAV is based on this build instructions)
At this point everything should be working. Just setup an account and check. To log in via email client apps you must use full email address as the username and the client must be capable of and enabled for smtp authentication.