Anyone know a shortcut for "Select a Label" sensitivity when creating a new email?

Every time I create a new email in Outlook, I always forget to select the sensitivity from the pull-down menu before hitting Send. When I'm in a hurry, this is annoying (yeah, two extra mouse clicks 20 times/day is also time-consuming..)

Anyone know of a shortcut or keyboard-combination to (pre) select "Internal?" Or better yet, to set the default of sensitivity to always select Internal when I create a new email? 

Regards, Jeff