Outbox has disappeared.IllegalStateException message in

A week or so ago, something happened to (corrupt?) my configuration.
I eventually discovered that Sent mail and Archive, for instance, were pointing to ordinary folders.
I have now set them back to the correct folders.

But the “Outbox” folder has dissapeared and if I click on the 3-line menu button, one of my ordinary folders has the “Box with an up arrow” icon next to it.

At the same time, I have a permanent error in my notifications “Failed to send some messages. IllegalStateException: No outbox_state entry for message with id 2833”

Can I do anything to fix this, or is it better to delete and do a clean install? I use MAPI, so the mails should still be on the server.

Thanks

The message database of that account is definitely corrupt. It’s best to remove the account and set it up again. If you want to be extra safe (because some other data might have been corrupted as well), uninstall the app and install it again.