I'm using Thunderbird 68.5.0 on Windows 10 Pro x64. I have tried to set up a filter that given the messages on a local subfolder of a POP account, marks them as unread and then moves them to a different folder. I use FiltraQuilla to restrict the filter to that specific subfolder. When I run the filter manually, it behaves correctly and only affects to messages the desired folder. But when I configure it to run every 10 minutes in the background, it never gets executed: new messages in the folder remain there even after hours of waiting. Is there any way of making it work as I intend? Background: I have a secondary account which people write to occasionally. I want to move new messages from that account's inbox into a subfolder of my main account and mark them unread so it's easier to see when new mail arrives, and at the same time I want the message on the inbox to be marked as read, so the "new mail" notification icon does not stick in the system tray. Moving them through a temporary folder is a workaround because Thunderbird, when applying filter actions, will always modify headers before copying/moving messages, so I can't create a single filter that copies the unread message and then marks the original as read (it behaves the other way, so the copy is always marked as read). AFAIK this cannot be changed, and thus I'm working on a workaround involving a temporary folder. But if this could be solved, the first problem would be meaningless.