[Dovecot] Make entire mailbox read-only (ACLs?)

Hello,

Is there a way of locking a mailbox, effectively making it read-only to IMAP clients?

I've read through http://wiki2.dovecot.org/ACL. I created dovecot-acl with the content "owner lr" in .INBOX which seems to keep me from copying messages into the folder, but not out.

I have the plugin configured correctly, it seems, since MYRIGHTS command shows the correct value:

30 MYRIGHTS "INBOX"

• MYRIGHTS "INBOX" lr

Am I barking up the wrong tree? Is there an easier way to lock a mailbox? post-login scripting perhaps?

Thanks!