I changed my ISP to Comcast recently, and again I’ve got issues running SMTP server. Basically, Comcast blocks port 25. I’ve come across this a couple of times now. I’ve decided that instead of trying to either a) complain and have them open port 25 for me (which I’ve had to do a couple of times) or b) try to work around it by getting someone to relay my mail, I am looking at instead moving this to Amazon’s EC2. If you’re not familiar with EC2, it’s Elastic Compute Cloud, and it’s part of Amazon’s Web Services. It lets you rent compute resources (and a bunch of other stuff) in the Amazon server farm. One advantage of this over what I’ve had before is now I would have a server still up and running (assuming that the Amazon uptime is correct) if my local server either goes down, or my ISP goes out (or if I move and change ISPs).
Anyway, I’m going to start putting some resources into a page for reference