deleting an eMail but not able to delete the belonging folder

[E. Zorn (RDG-rational)]

Hi,
we are using cyrus with Outlook as an IMAP-Client.

How can a User be able to delete an eMail but not be able to delete / move
the belonging Folder?
I looked at the possible rights from cyrus but I have no idea. Looks like it
is impossible to do it with the rightsmanagement of cyrus. Has anybody an
idea for an workaround.
The stupid users here are often moving there folders in outlook.

Any Ideas?

-Elmar