This may have been asked elsewhere, but the only similar questions I can find are for the iPhone. My Mac Messages app has 1 phantom unread message. I can work my way through the whole list of conversations and none have a blue dot; selecting each in turn also doesn't fix it. Rebooting removes it temporarily, but it always comes back. The unread count does update--if I get a new message it increments--but it will never count down below 1. The phantom message is apparently in my T-Mobile text bill announcements. I say this because if I right click on the Dock icon, it shows "456 (1 unread)" at the top (456 is the T-Mobile bill announce text number), and if I select that it jumps to that conversation. However, there's nothing unread there. In fact, even if I right click on the conversation and permanently delete it, the Dock icon still shows that same conversation. (Selecting "456 (1 unread)" from the dock right-click menu after deleting the conversation brings the window forward with nothing selected.) I also tried scrolling through the whole conversation on my iPhone and deleting it there, still no luck. Any suggestions? I'd kind of like to avoid purging all past conversations by wiping preferences, and I'm not sure that would fix it anyway.