Ctrl+Shift+I 
Switch to Inbox.

Ctrl+Shift+O 
Switch to Outbox.

Alt+Enter 
Display message properties

Ctrl+A 
Mark All

Ctrl+Shift-B 
Open Address Book

Ctrl+C 
Copy selected text

Ctrl+D 
Delete selected message

Ctrl+E 
Opens People Search Dialog

Ctrl+F 
Forward to selected message

Ctrl+Shift+F 
Open Message Search Dialog

Ctrl+G 
Follow-up to newsgroups

Ctrl+N 
Create new message

Ctrl+P 
Print selected messages

Ctrl+R 
Reply to the author of selected message

Ctrl+Shift+R 
Reply to author and all recipients of selected message.

Ctrl+U 
Display next unread message

Ctrl+< 
Display previous message

Ctrl+> 
Display next message

Ctrl+F2 
Open message body in Notepad

Ctrl+F3 
Display message source code

Esc 
Close window