You naysayers can believe what you want to believe, I'm just telling you the message that I read online when I logged into my email on my Mac. The message was that the servers were down for maintenance.
My Comcast email went down at about 3:00 this afternoon - on all of my devices, iPad, Mac and iPod Touch, no way I had the wrong settings on all three devices. I got the message on my iPad that the username and password were wrong and I knew that they were correct. I have been using Comcast email for over 12 years. When I logged onto webmail with my Mac, that is when I read the message about the servers.
Call Comcast instead of stressing or wondering about it. They can confirm one way or the other.