That's a pretty neat idea (you should retry your link - it doesn't point to the tarpit entry ;->). As it is, I've reduced the bandwidth by getting my SMTP author to reject email when my filteraddress perl script says to reject it, and then to disconnect after about 4 incorrect commands - most MTAs that send spam seem to ignore the reject command, and just send the rest of the email immediately anyway, which results in hundreds of bad commands to my SMTP server. So the SMTP server now just disconnects after a few bad commands, and I don't even see the rest of the email - it's blocked partway through the header.

The tarpit idea is even better - if I could just delay the rejection by a second or two, then disconnect after 4 bad commands, that could have a beneficial effect. At least that system is a good multitasker with usable threads ;-) otherwise I could overload the system with this - all these extra processes waiting around.