That's not the fucking point. What about people sending emails from two way pagers such as blackberries? cell phones? danger hiptop's? other such devices? handsprings with the cell phone plug in, cell phones that are also pilots? something sitting in an embedded controller that has a tiny tcp stack and sends status emails? Not every object capable of sending email is going to be reprogrammable, nor will it have the proper CPU power to sit there and crunch a problem. Further, what about anonymous mail from remailers? no return address there. This is a lame way to get rid of spam and puts strain on the sender to prove he's not a spammer. Do you really think someone is going to sit there and do a puzzle in her head just so she can send you an email from her blackberry just because RIM or whatever network hasn't adopted your pet anti-spam authentication project? No, she'll give up and not send you the email. If something is a suspected spam, it's not necessarily correct to have it prove itself by replying to a challenge. It may not be possible to do so, or may be a hassle to the sender. It's upto you to set your filters correctly or make sure that things that aren't spams aren't marked as such. Either way, this is not going to work. It sounds good in theory, sure, but in real life, who's going to bother going through the hassles? How many millions of ISP's are you going to have to convince? How many thousands of SMTP servers and mail clients are going to need to change? And even if you do succeede in making the above happen, which you won't, what makes you think the spammers won't just pool their resources together and buy clusters of machines to authenticate themselves past such schemes? Intel hardware is very cheap these days and getting cheaper. They'll just raise their costs and charge their clients more for "Super duper guaranteed to be delivered past the spam filters spams." $1 for a million spams, $100 for a thousand guaranteed to be delivered past the filter spams. Think like they do. Thinking like a geek is great. But if you want real people to use your stuff, the hassle factor is a huge thing to overcome. And if the spammers simply get around the problem, then what? Pass laws? Ok, how are your CA or TX anti-spam laws going to apply to some shithole ISP in Afghanistan? So you find their IP's, so what? Sue them? Go ahead. ----------------------Kaos-Keraunos-Kybernetos--------------------------- + ^ + :25Kliters anthrax, 38K liters botulinum toxin, 500 tons of /|\ \|/ :sarin, mustard and VX gas, mobile bio-weapons labs, nukular /\|/\ <--*-->:weapons.. Reasons for war on Iraq - GWB 2003-01-28 speech. \/|\/ /|\ :Found to date: 0. Cost of war: $800,000,000,000 USD. \|/ + v + : The look on Sadam's face - priceless! --------_sunder_@_sunder_._net_------- http://www.sunder.net ------------