My comments about evangelizing spammers have drawn some positive attention. I want to clarify one thing. Unfortunately (for evangelistic purposes) most spam does not contain the real email address of the spammer. Evangelistic replies could simply result in a lot of "undeliverable" messages bouncing back to you, or--worse--be routed to an "innocent bystander" whose email address has been "borrowed" by the spammer to list as the sender. (I know this happens. I get spam messages that say they're from me!)
Over time I have learned to recognize the spam that has legitimate reply email addresses. Usually they take the form of messages saying the sender is dying and needs help distributing a large sum of money to an honest person, or wanting to buy a large quantity of products from my business.
When I reply to these spams, I almost never get an "undeliverable" message back. Most of the time the spammers do not reply, but at least I have the joy of knowing that they received and read my message. May Jesus water the seed of His Word in their hearts and cause it to bear fruit in due time.