When choosing a mail client I wanted one that avoided proprietary formats, like those used by Outlook and Outlook Express. Mozilla/Netscape has had a history of keeping mail files in plain text format, which makes importation and manipulation easy. I also like Thunderbird because it supports SSL enabled POP and SMTP, which according to Comcast they support too. SSL-enabled POP works fine, but this is as far as I get with SSL-enabled SMTP:
21:59:52.049456 IP 192.168.2.4.4067 > 22.214.171.124.465:
S 1728039870:1728039870(0) win 16384
21:59:52.133043 IP 126.96.36.199.465 > 192.168.2.4.4067:
S 640665924:640665924(0) ack 1728039871 win 65520
21:59:52.133152 IP 192.168.2.4.4067 > 188.8.131.52.465:
. ack 1 win 17640 (DF)
As you can see I can complete a three way handshake, but there the process hangs. I posted this to the support forums (reg required) and to their feedback form. I can't wait to see the replies. Update: I received an email stating this could be a problem with Thunderbird.