Troubleshooting & messages · Moves and copies that didn't finish
Why does it say Mail changes these files constantly, so they can't be moved?
Short answer: Mail rewrites its data constantly while it's open, so moving it then could corrupt your mailbox. Quit Mail completely and try again.
Mail rewrites its data almost continuously while it's open, so moving it out from under Mail could corrupt your mailbox. Storage Studio won't do it while Mail is running.
### What to do Quit Mail completely, then try again. If Mail is set to open at login or reopens itself, quit it right before you start the move.