Preventing users from deleting a spam folder.

[Matthew Schumacher]

Hello,

I would like to start moving spam into a spam folder for each of my
users instead of dropping it, then deleting it after a few weeks.

Expiring the email looks simple enough, but I can't quite seem to figure
out how to create a spam mailbox they can't delete.  If I create a
user.fred.spam mailbox and set fred to only have read permissions, it
gives the user admin permissions which allows the user to delete the
mailbox.

What is a good way to go about this?  Re-create the mailbox if the user
deletes it?

Any suggestions really appreciated!

schu