I have a suggestion, could the spam filter separate the messages which 
people mistakenly try to unsubscribe with and a script run that emails 
them back saying:

"This is an automatic email sent out by the unsubscribe function.

Your email to unsubscribe has been unsucessful due to the fact that it 
was sent to the wrong address.

Please email listname+unsubscribe@g.o to complete the 
unsubscription process

Gentoo lists management"

Or something similar.

Good? Bad?

George
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