I know I'm a couple weeks late posting this, but the fine folks at Mozilla finally released Thunderbird 2.0. Now, I've wasted a lot of your time here in the past waffling between mail clients... but I've been using thunderbird consistently since the 2.0 betas and I think it might finally stick. Here's why (for me):
- Favorite folders: this feature allows you to mark certain folders (email folders, RSS feeds or saved searches) as "favorites" and you can limit the left-hand pane to view only those folders. For me, since I use procmail heavily to sort mailing list traffic, etc. this is a great feature for seeing my most "important" folders.
- UI updates: like Firefox 2.0, Thunderbird got some subtle yet very pleasant UI updates - check them out for yourself. I also like the sound of this hack to make tags look prettier.
- Tags: like the old "labels" messages can now have optionally multiple tags. I know after I read GTD I'm going to love this one even more.
Also, while not a core feature, I'm very pleased with the new Growl add-on for new message notification (I had been using YAMB before which wasn't optimal.
Still on my wishlist: sender pictures (preferably from LDAP userpicture or mac address book integration) and better offline detection for OS X. Otherwise, I love it.