As part of moving to my new laptop I've also decided to give Mail.app a try and so far it's going well except for two things I've been unable to figure out how to do:
1. Mark all the unread messages in a folder (err mailbox) as Read.
2. Create rules to filter outgoing messages.

Someone fill me in? Discuss

I gotta say though: thread colouring is excellent and the spam filtering seems to be working really well, despite other reports I've read to the contrary.