I'm setting up a new computer with windows10 and I've set the outgoing server to smtp.comcast.net with the same settings as on my win7 computer, user name, port, and password. Xfinity/comcast does not recognize the combination of username and pw from the win10 computer. I've logged in to comcast site from the win10 using the same username and pw, with no trouble. It's only the outgoing email that's a problem. The live agent wanted to blame my modem, which works with no problems including comcast site, or my new computer, which has no problem with the internet including the comcast site. He was unable to kick it up to the next level and unable to give me an email address to send details. User's recommendation: good luck.