I just love some of the anti-spam measures put into place.
A member of one of the mailing lists I run had put into place a challenge-response anti-spam measure, where you have to reply to the message in order for the original message to go through. Only the challenge-response message gets bounced back to the list as a whole! (Fortunately, the challenge-response system is smart enough not to cause mail loops when the challenge-response gets sent back … ) Bad enough, but now, another member has classified the challenge-response messages as spam!
We got email bouncing everywhich way as anti-spam software tries to deal with other anti-spam software, each claiming the other as spam.
There's a Monty Python (Who would have thought people can't spell Python?) [1] sketch in here somewhere.