Since upgrading to hashcash-1.16, I've become aware of an issue with hashcash not validating the token when executed through procmail. Unfortunately I upgraded from v1.13 so I'm not exactly sure when the problem was introduced, or even if it is a hashcash problem or something else. Procmail Recipe: :0 * ^X-Hashcash: * $? hashcash -cqXdp 1d -b24 -f $HOME/hashcash/hashcash.db -r testing | ~mail2news/bin/multipost When I fire an Email through this recipe, I get the following log: procmail: Match on "^X-Hashcash:" procmail: Executing "hashcash,-cqXdp,1d,-b24,-f,/home/mail2news/hashcash/hashcash.db,-r,testing" procmail: Match on "hashcash -cqXdp 1d -b24 -f /home/mail2news/hashcash/hashcash.db -r testing" procmail: Executing " ~mail2news/bin/multipost" The Hashcash header on the Email is: X-Hashcash: foobar Nothing is logged in the hashcash.db for this message, which suggests that hashcash rejects the invalid header, but the procmail action is executed. Any suggestions what might be causing this?