I've made Outlook Actions as well, where I've tried to make it similar to the Outlook Express config and with recognizable elements from other widely accepted gestures (like back/forward, refresh):
Check Mail [M or Up-Down]
Next Message
Previous Message
New Item [N]
Reply [R]
Reply All [A]
Forward [F]
Show Address Book
Grr, why can't you edit posts here, that is very unhandy. People need to scroll all the way down then too, can't just continously update one post with the latest version...
I made a mistake, Down-Right is used for "Close Window", so I've changed the gesture into "D".