said by banditws6 
:Running a mail server on a residential connection is a big risk. If hacked, it could pose a significant spam threat. I realize you are the sole authorized user of the server and you're not offering it to others, but it's still not something I would do.
Other than mail and web servers, if you had been doing anything else with open ports, Comcast probably would look the other way. If you have to forward a port for some online game or voice chat app, for example, I doubt they're going to make a stink unless they really, really want to lose a customer for no practical reason.
If you need to host your own mail server for some business-critical reason, perhaps you could rent a server at a datacenter. Does Comcast Business Class allow you to run a mail server or some such thing? Knowing them, probably not.
I was running Microsoft Exchange 2007 to learn how it works so that when I go back to work in June I have a better understanding of the products that we use and sell to our customers. The OWA site was running on port 80. I was the only person using the mail server.
