I have a spamgourmet address, with exclusive sender set to openoffice.org (I use this for the openoffice mailing lists). Most messages sent through the mailing list get through as exclusive sender, but I have just received one which didn't, and hence decremented the remaining message count (would have been deleted without my knowledge if the count had reached zero).
The To header is:
To: users<AT>openoffice.org, an.other<AT>example.com
(I've replaced @ with <AT> and changed the other address, to prevent them from being picked up from here by spammers!, but hope that's clear for describing the problem)
The X-Spamgourmet header is:
X-Spamgourmet: (openoffice: message 11 of 20)
Indicating that this has not been detected as an exclusive sender. The To: header contains an address matching the exclusive sender (openoffice.org), so why would this not have been detected as an exclusive sender? Is it possible that presence of the second address in the To: header causes a problem?