Lots of good recommendations here.

Slightly off-topic, but maybe someone can help me relay around a residential Comcast block?

I've asked this question before - but didn't get (or understand) what I need to do.  I know I need to switch from port 25 to port 587 and this may involve some cryptography.   

If anyone actually has this working with Postfix or sendmail, I would be interested in duplicating your solution.  I don't need anything fancy - just want to run some Mailman lists out of my basement.