To those who said it couldn't and/or shouldn't be done -- the power of USERS will always prevail! Long live user-centric computing (and, yes, as someone who lives and breaths computing and programming let me assure you this is a VERY useful and effective capability in many instances).
* Note: I have sucesssfully tested this on OS X Lion (10.7) and OS X Mountain Lion (10.8) Developer Preview 1 through 3 *. Credit goes to Kevin at Techie Manager for the original code.
1. Run the automator
2. Make a new service (or application)
3. In the drop down menus select “no input” in “Mail” in the main window
4. Drag “Get Selected Mail Messages” into the workflow from the pane on the left
5. Drag “Run Applescript” into the workflow
6. Insert the following code:
on run {input, parameters}
tell application "Mail"
repeat with eachMessage in input
bounce eachMessage
end repeat
end tell
end run
7. Save as "Bounce it Right Back!!!!" or anything you like.
8a. In Mail, select a message. Click the “Mail” menu up top--> “Services”-->"Bounce it Right Back!!!!". The message will bounce =)
8b. This is useful for many situations (e.g. ex-boyfriend keeps writing you, you can't deal with a message at the moment, you're on a stubborn mail list) but if it's spam and your bounce bounces back then get the raw source of the message, copy it, and go paste it as a report at www.spamcop.net
9. Come back to this thread and be supportive 🙂 of myself and the original poster
10. Have a great day!