Thunderbird + smtp authorization

[ctav01]

I want to be able to send (just send) e-mails from my Gentoo box using Thunderbird. I had this working at some point in the past but now it doesn't work. I think the problem is in the smtp authorization. I can set my user name in Thunderbird for smtp.comcast.net but it never asks for my password. I tried setting up KMail but it also fails when sending.

I looked through various threads and found lots of references to Postfix and SSMTP and their configuration files but it turns out I have neither installed (so no config files to edit).

I'm obviously no expert on any of this so any suggestions would be welcome. Thanks in advance.