This works perfectly in my Linux box with Thunderbird, will do this on my windows laptop tommorrow.
"Comcast servers will not except IPv6.... Disable it in Thunderbird: Here's how: in Thunderbird, goto Edit>Preferences>General Tab. On the General screen, select "advanced" tab > "General" subtab, and in the lower right corner find the button "Config Editor" Click on it, acknowledge the warning, and scroll a long ways down to: network.dns.disableIPv6 (default: false) Double-click on the line, and the value will change to "true" Back out and Okay, shut down and restart Thunderbird, and your client will connect to the imap server in a flash."
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