I use Expiry on most of my (IMAP) folders. On less important ones, expiry
permanently deletes messages. That works fine. More important folders, I set
the expiry to move them to server/Trash, where they stay a little longer
before being permanently deleted. At least, that has always worked before.
Now I'm seeing, on the F10 netbook "Moving old messages from folder KDE-fedora
to folder Trash failed".
My 4.1.3 laptop can still expire them, so although I've not been aware of when
this started it's probably quite recent.
Anne