I use Thunderbird with Comcast, but I don't have a clue why you are getting redirected to the gandi site. However, here is a current list of settings provided by Comcast:
Using Email Client Programs with Comcast Email
Personally, my POP server port is 110, and the outgoing smtp port is 587
The password you need to tell Thunderbird is your Comcast password. That allows TB to access your email from Comast for you.

I hope this helps a bit. Good luck!