I have an 1Phone 6 and just recently did an update to IOS 8.3. I had the same issue as those above over the last few days. I deleted my comcast account on the phone, and added a new one (which found Comcast settings and defaulted to them) and it worked. I would suggest doing the same-delete your old Comcast email account on your phone and create a new one. Problem solved and it only took me 30 seconds.
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