Man, this is one of the least intuitive processes ever. OK, someone explain to me how this works. I have my IMAP acct set up in Mail. I right click on "Inbox" and make a new mailbox underneath that.. let's call it "Blah". After doing that, there's a triangle next to Inbox and I can expand it. But after closing it or navigating to another mailbox, it folds up, and I can't expand anymore! "Blah" is totally inaccessible.

Also, getting the standard Sent/Trash/Drafts folders to show up was a task. I had to create them manually for some reason under "Inbox", then go to the menus and for each folder, choose "Use Folder as... (Sent/Trash/etc)". After restarting the Mail app, the folders properly showed up on the left.

I also don't like how when I send off a message, there's no progress meter, nothing. It's like, "your message has been sent off into the void.. its progress is unknown."

Kinda weird.. I guess I'll get used to it. I'd use Thunderbird or something, but I like Mail's integration with iCal and Address Book.