Switch to next message (with message open).
CTRL+PERIOD
Switch to previous message (with message open).
CTRL+COMMA
Send.
ALT+S
Reply to a message.
CTRL+R
Reply all to a message.
CTRL+SHIFT+R
Reply with meeting request.
CTRL+ALT+R
Forward a message.
CTRL+F
Create a message (when in Mail).
CTRL+N
Create a message (from any Outlook view).
CTRL+SHIFT+M
Sum Numbers Listed Above
Alt + =