Hey all... This isn't really a security question, but anyway...
I'm currently working on a feasibility study for the implementation of a network. I am offering three possible solutions..
The solutions are..
1. A Windows 2k centric network
2. A Linux centric network
3. A meshed one, involving linux servers and Windows workstations...

Here is my question... I am going to recommend the meshed solution, however, I need to provide a Mail Server for the network.. Does anyone know a good Mail server for Linux.. it doesn't have to be cheap (if it costs anything), as I can justify the expenditure through the savings by using linux..

Thanks in Advanced...