Mavericks, Spamsieve 2.9.10, Apple Mail junk filter off, install Apple mail plugin done and Apple mail restarted. I select mail in the spam folder and choose “train as good” from the message menu. The message is moved but then ends up back in the spam folder. Never had that happen before.
It sounds like you have another computer whose rules are filtering that message.
Yes that was the problem. Thanks!
Please also see SpamSieve and Multiple Macs.