Comment Depends what sort of solution you will accept (Score 1) 405
If you want to win this, either as a technical challenge or a test of wills between you and Comcast (or Goolge/Yahoo/Microsoft), good luck. Maybe you'll resolve things in a satisfying way eventually. If you do, you will definitely feel like a champ, but it's going to take you a lot of time and frustration to get there.
If you simply want your email server working, then you probably ought to consider sidestepping the fight and just solve the problem instead. You could move the server from a machine hosted in your closet to a VM running on a cloud service. Done right, you can probably increase performance and availability while lowering cost (that 24/7/365 electricity isn't free).