[Dovecot] Forbidding folder delete

Is there some way I can forbid the deleting of folders?

I have a Thunderbird user who twice now has accidentally deleted a folder, forcing me to go fetch it from the nightly backup. I'd like to prevent this from happening again, and the easiest way to me is to block folder deletion. I'd rather do that "manually" from the shell than leave it available from the client GUI.