Mail.app: Resend a Message
Contributed by shamanstears 
July 13, 2008 
Tagged: Mac OS X Leopard
Sometimes you need to resend a message either because the recipient never received it or because they accidentally deleted it. To do this…
1. Select your Sent box.
2. Double-click on the message that is to be resent.
3. When the message opens, go to the Menu Bar.
4. Click on Message and select Send Again or use the keyboard combination of Shift+Command Key+D.
5. When the message box appears, click Send.