Includes: Shorewall, NAT, Caching NameServer, DHCP Server, VPN Server, Webmin, Munin, Apache (SSL enabled), Squirrelmail, Postfix setup with virtual domains, courier imap imaps pop3 pop3s, sasl authentication for road warriors, MailScanner as a wrapper for SpamAssassin, Razor, ClamAV, etc. Samba installed, not configured.
Read it here at howtoforge
Scope: creating a firewall/(mail)gateway for a small network (say 10 to 15 users or so on a PIII 450MHz, 512 MB ram and two identical network interface cards, broadband connection, fully featured, for a business environment. Better specs of your hardware (notably the amount of ram) will improve the performance of your server significantly. The specs mentioned ar a bare minimum for not so demanding customers, yust to indicate that if you really want, it can be done indeed (need to do some tweaking afterwards though).