Hi Max,
First of all, one noob question: how do I make sure my mail is recognized as a reply to an existing post in the mailing list? I have tried clicking in the e-mail address on the mailing list page which automatically generates an e-mail with the correct header … but usually it isn't recognized as a reply to existing posts :-/
Hitting the "Reply" button on the email you'd like to reply to should do the trick :-)
-steve