I’m a bit confused by the fact that Mozilla is preparing the first alpha release for 1.5 despite the fact that it won’t be the new combination of Firebird and Thunderbird that future releases of Mozilla will eventually be. I thought that 1.5 release was where that transition was going to be made, but I guess that’s not the case. (It wouldn’t make much sense for the 1.5 alpha to be the old Mozilla Applications Suite and for the beta to be Firebird, would it?) Anyway, I’ve been using both Firebird for browsing and Thunderbird for mail for a few weeks now, and despite the fact that they’re theoretically pre-alpha, I haven’t had any problems with them to speak of. Thunderbird is still a bit rough around the edges in terms of fit and finish, but not in terms of stability. It hasn’t munged my IMAP email at all, and I don’t think it has crashed once.
Looking at the roadmap, I’m thinking that version 1.5 will concentrate on items 4 and 5 under the heading “a new roadmap.”