I am a Comcast customer for many years. I have 3 comcast email addresses that I use regularly. Yesterday I noticed that none of my emails from any of my 3 accounts are being sent. They say they are sent and they show up as sent in the outbox or sent file, but no one is getting any of my emails. I can receive emails on all 3 accounts, and if I email myself from a gmail account, I get that, but nothing is being sent outbound by my Comcast email. I'm using Thunderbird, on Windows 7 the same way I've been using it for may years with no issues.