I am running 10.10.2 Spamsieve 2.9.19 and Mail Act-On 3.1.3b1666
I have set MAO so when I press F2 I have a choice of a letter with which to color a message by a given color.
Sometimes, not always, I press F2 and another letter and instead of coloring the message it is marked as junk as Spamsieve does. I click, not junk and repeat the process and my message takes the color I need.
This is happening since the update to 10.10.2 or to the latestst Spamsieve.
Have you reported this to Indev? It sounds like maybe Mail Act-On is invoking the SpamSieve rule on that message. You can tell for sure by checking SpamSieve’s log.