Rogue Detect sends DHCPDISCOVER packets to the network and listens for DHCP servers to respond. It can run continuously as a daemon, or do a single probe and quit. It's written in Perl and can be easily extended to take any action you can think of in response to an unknown DHCP server (send pages, disable them, etc).
Artica for Postfix is a secure Web interface for Postfix administration. It is designed to reduce the cost of creating and managing a full Linux mail server. It supports Postfix, Kaspersky Anti-spam, Kaspersky Anti-Virus, Bogofilter, Milter-greylist, SpamAssassin, Clam Antivirus, Amavis, OpenLDAP, SQLite library, Cyrus-imap, Procmail, Fetchmail, DnsMasq, Mailman, Sieve, Yorel script, QueueGraph, MailGraph, AWSTats, geoip, and more.