We all know 37signals for their products like Basecamp, Highrise and others but also their advise on building web apps and running a company like ReWork.

They are very public on how they do things and they have published a blogpost on how they run their mail servers. It’s a very good read with lots of tips and links to services and solutions that if you run your own mail server are very useful. Things like having reverse DNS entries (a must), domain keys and more are explained. Follow their advice if you want your mail server to actually deliver most of it’s email.