This letter uses the hard-sell approach and turns it on the spammer, using hyperbole and plenty of loud capital letters to let them know to stop sending ads.
For a limited time only, you have the opportunity to GO AWAY! That's right, for as little as NO MONEY you can stop sending "spams" to my e-mail box and let me get my work done in peace! No more annoying me! No more <description of how ads waste your time>. Just THINK of the opportunity. You can spend time bothering millions of others! People who might actually BUY your <name product/service>. Because I certainly won't. So ACT NOW! Get in on this fabulous opportunity to make the world a better place. Stop sending me your "spams" NOW! How can you do it? Volume, volume, VOLUME! Hope you get the picture.