Why is there never a perfect piece of software.
Wanderlust almost all of what I want, but it has several annoying bugs/misfeatures:

• It’s single threaded, so if it get’s stuck during an imap sync, the whole damn thing get’s stuck, the whole emacs session is stuck
• It doesn’t have any way to tell you that there’s a hidden unread message under a collapsed thread
• It get’s coloring wrong when you’re doing an inline reply.. it seems to get the first block of your text right, but then every other

But then, mew isn’t perfect either:

• It’s very conservative about threading, so that it misses some threads sometimes
• You can’t look at imap folders with spaces in the names.. thankfully they’re all of the for “%Public Folders/…” so I don’t care too much
• Why can’t I highlight unread messages? Isn’t that like a super-basic feature?

And neither can do automatic mail checking too well. Is that so hard to do?
Update
Doh! I know, I know… RTFM. Turns out mew has biff-like functionality and it actually works better than wl’s. The appropriate code being:

(setq mew-use-biff t)
(setq mew-biff-interval 3)

The second bit is to set the check interval (in minutes).
I wish there was a hook into it so that I can make it more obvious (maybe hook it up to growl in the future).