Last night at 3 AM, The Bat! v.11.4.3 (which I had upgraded yesterday) suddenly decided that all the messages in my inboxes were unread and started playing three different sound clips for about 700 old messages! I suspect the culprits were filters that had worked perfectly before the update.

My immediate half-asleep solution was simply to mute the computer. This morning, for a hopefully permanent fix, I deleted the “Play sound” action from the filters and recreated it. So far, it seems to be working.