Mail server question

I am returning to the idea of building a web and mail server setup at 
home for learning practice.  I was considering running Kloxo for a 
webhosting control panel, but I read that it doesn't support anything 
other than it's internal mail system:

"Q:  Does support Postfix, some antivirus (ClamAV), Horde and other 
IMAP/POP3 servers (dovecot, cyrus)?
A:  clamav is used.  No support for other MTA's and IMAP/POP3 servers."

I am seeing indications that Kloxo uses Courier and qmail for mail 
services.  I was thinking about going the DoveCot/EXIM route.
Are there significant differences between these that would make working 
with other server software a challenge, or are basic management 
operations the same amongst mail server software to the degree that I 
shouldn't be concerned about it?
I want to make sure I am teaching myself in a way that makes me as 
flexible as possible in the job market.

-T