There are a huge range of email server products available.

I won’t beat around the bush, in my honest opinion, most Postfix based systems are by far the most practical and effective. The main reason for this is that Postfix is free and flexible.

A fantastic, sophisticated and clever email server software system is the Zimbra Collaboration Suite (ZCS) Open Source Edition. When I first attempted to install it, things got sticky. The main issue for me was that it needs a DNS server present which needs to point to itself (internal IP address) for all domains you add to your Zimbra system.

When I eventually figured out how to install and configure BIND on my email server, everything started to flow.

Zimbra does complain here and there but, after your third or fourth install attempt you will find it works with very little extra effort. Go ahead and try it. Once you figure out the requirements, I promise you’ll be impressed.