[Dovecot] anonymous mailing list archive configuration?

Hi,

I'd like to run a mailing list archive via IMAP like for this list but my mails are in maildir and not mbox.

It's easy to add a new user that has access to the maildir that mails get stored in, and I can simply link that up to that user's inbox. It's also easy to prevent putting mail into that folder.

However, one thing I'm not clear on is how to prevent that user from creating new folders. I don't think I can do that with permissions to the ~/Maildir since that user needs to be able to create files there for indizes etc.

Is that possible? Should/can I write a plugin that prevents things?

johannes