(*
Set Mail.app Message Sender

By Matthew McVickar

Description:
Mail.app's AppleScript library does not allow access to the properties of the outgoing message object. The only way to change those properties is by GUI scripting. This particular script changes the sender of the message. If you have, for example, personal and work email addresses between you switch often, this script is essential.

Instructions:
Change the 'X' in the fourth line of the script below to the number in the 'From' dropdown that corresponds to the email address you want. (E.g., if the email address is the second one down the list, put a '2' in there.

*)

tell application "System Events"
	tell process "Mail"
		click pop up button 1 of window 1
		click menu item X of menu 1 of pop up button 1 of window 1
	end tell
end tell