A e-mail server wrapped in a snap, designed to be easy to setup and maintain.
Running an mail server can be daunting, here are a bunch of different things to keep track of. You need to choose what software to use. Figure out how to configure it (properly) and how to maintain it.
If you are a seasoned sysadmin that prefer to tweak your systems to your likings this may not be for you. If you like a quick and easy way to run a fully functional e-mail server this is exactly what you are looking for!