Cant send HTML formatted mails... It doesnt work, only sending plain text is working ok...
And it also seems Thunderbird is still lacking all HTML formatting tools Mozilla has...
I guess I have to wait a few versions before dropping Mozilla as my main mail programm
(also junk mails seems to be a little bit better handled in Mozilla, but maybe I didnt test Thunderbird long enough to confirm this. v0.7, tested three weeks)