Captive mailbox in Cyrus IMAP?

[Nik Conwell]

We're currently using UW IMAP and have previously implemented a hack  
whereby accounts (based on shell name) are designated captive.  For  
these accounts, any SELECT of any folder is overridden to SELECT a  
read-only shared mailbox with a single e-mail that tells them they're  
captive and what they need to do to get out of the situation.  To the  
client it looks like you've lost all your e-mail and you only have a  
single message.  In reality, the e-mail is still there and delivery  
continues to work.  Getting them back to their normal mailboxes is a  
quick/easy operation.

Is there any way to do a similar thing in Cyrus IMAP?  I'm not  
against coding it but I wanted to see if there was a conventional way  
of doing this first.