Trying to get mail working

I have charge of a very mixed system--current OS (Fedora 20--OK 21's out but I just haven't upgraded yet), current (or nearly so) Mailman (2.1.18-1), Postfix 2.10 with a configuration file sfrom something a lot older which I've run through the upgrade-configuration procedure, and old Dovecot (1.0.15). Is there anything I can do to test each of these components individually, then add a second component and test the three pairs, then all three together? I am nobody's definitioin of an expert in any of these three components, so am having a lot of trouble making them work together, so I thought maybe there might be some test procedure that might straighten me out.

Thanks in advance.