King Phisher is an open source tool that can simulate real world phishing attacks. It has an easy-to-use, flexible architecture that allows for full control over both emails and server content. It is useful for running awareness campaigns and training, and can only be used for legal applications when the explicit permission of the targeted organization has been obtained.
PyEximon is a GNOME monitor/manager for the popular MTA, Exim. It includes real-time status graphs and log updates, colored log browsing, hierarchial message lists, as well as a graphical interface to common message functions.