Most of you know that there are a number of different distributions and mail transfer agents that could be used to build an equally capable mail server.
The only other mail server I had experience working on is build on
CentOS and it is called
Qmail Toaster. Qmail Toaster has a lot of
strengths. It is a ready made software library which you can install and
the installer will take care of setting up a bunch of different programs
and utilities that are needed for a mail server.
On the other hand, from what I have seen, it has it's share of quirks and the biggest one for me is that it uses Qmail. Qmail is not a bad MTA (Mail Transfer Agent) but it is not being actively developed for years and a lot of the functionality is provided through patches.
Postfix is on the other hand an actively developed project and all of the requirements a modern mail server could have are either present in Postfix itself or they can be provided through other applications.