Per-user special folder?

Hi

It's possible to mark some folders as special use for IMAP in the config like:

namespace inbox { mailbox Spam { special_use = \Junk } }

Our webmail allows users to use an arbitrary folder for Spam, and we have this settings and we'd like to return it in from our UserDB (which is a custom dict proxy).

For testing were able to set a namespace parameter like "separator" by returning: "namespace/inbox/separator" : "=",

from UserDB, but can't figure out a way to set mailbox settings,

"namespace/inbox/mailbox Spam/special_use" : "\Junk", for example doesn't work.

Is there a way to return this setting from a UserDB query?