Mail.app - There's no way to unsubscribe a folder! If you're on an IMAP server that has hundreds of shared folders, each of which contains thousands of messages, it's basically impossible to use Mail.app. I'm forced to use Thunderbird, which in almost every other aspect is a far inferior program.
Anyone else having this problem? Really wish Apple would fix it so I can use my favorite mail client again!!!
What's bugging you?