[Dovecot] Sub-folder outside of the mail store

Hi

How do I create an IMAP folder that links to a folder outside of the mail store?

For example, I have all domains under /var/spool/mail/virtual/domains.net/ and users under /var/spool/mail/virtual/domains.net/user

Amavis delivers quarantine mail to /var/spool/mail/quarantine

I would like one user (postmaster) to have a folder /var/spool/mail/virtual/domains.net/postmaster/.Quarantine and link it to that folder - is that possible? Is it safe? The client the postmaster uses can then reinject and deliver the mail if need be (i.e. it's safe or the attachment has been stripped).

Thanks.

Simon