Problems sending emails from iPhone 4 via comcast

[Wellspolypro]

I am unable to send emails from my iPhone using my comcast account, my mac account works fine. Talked to comcast at great length and they are unable or unwilling to solve the problem, they think it is an Apple problem. Funny thing was some of the people that work at Comcast are having the same problem. There solution was to download the Xfinity app and send and receive emails from the app, a pain but doable. Any suggestions? All the settings, etc, have been verified ad infinitum so, that's not the issue.