This has come back again. I am sending myself email from work computer and Gmail works fine. Comcast email just never shows up. Stopped using web client and went back to desktop Apple Mail. Deleted all settings, cleasred cache and started from scratch. Got Gmail, Yahoo, and an old AOL account working, but not Comcast. This makes Comacast mail untrustworthy and unusable. I have this account linked to a credit card and I am not receiving receipts from purchases. Embarissing when I have to ask a Doctor to send email multiple times and then switch accounts.
I see other related threads that are closed, but the issue persists.