Spam is a numbers game. If you make it harder for spam messages to be sent out, spammers 1. send less spam by default 2. increase hardware. (realize 2 can also

Spam is a numbers game. If you make it harder for spam messages to be sent out, spammers 1. send less spam by default 2. increase hardware. (realize 2 can also include increase cost if not using a "free" bot-net) If all SMTP servers were required to receive and send back a token/packet before their original message was delivered, the bandwidth/cpu etc... required to send the message will have increased. Send original to recipient server, receive from recipient server, send to recipient server. Then the mail is delivered. Example: A single spammer can send out 50 million emails / month on current system. Introduce a 3-way & that number drops. If the spammer wants to get back to sending 50 million / month, a significant increase in hardware will be required.