I am researching what are the most popular Linux and server based email systems out there. I want to use a company wide email server system but don't want to use Novell GroupWise, Microsoft Exchange, or Lotus Notes/Domino. Well, unless these systems are major players in the Linux market.
Anway, hopefull for a Linux guru this is an easy question. What are the top 2 or 3 Linux and server based email systems people are using, and which ones are becoming the Linux and market leader? Then, what email clients are people using for these email servers?