Fatal error with IMAP MOVE from a shared mailbox to Trash folder

[James Cassell]

On Tue, Dec 27, 2016, at 11:35 AM, Daniele Barresi wrote:
> Hello everyone.
> I have a problem using Dovecot 2.2.26 with ACL plugin and deleting e-mails
> from a shared mailbox.
> 
> My user doesn't have the "expunge" permission on the shared mailbox, but it
> has the "write-deleted" permission. So, when I delete a message from the
> shared mailbox using a client that implements the IMAP MOVE command, it
> tries to move the message to my Trash folder. Then the server closes the
> connection to the client (process aborted) and I get three lines in the log
> file with a backtrace and "Fatal" error. In this case the message doesn't
> get copied or moved from the shared folder and the client complaints. I
> found the same thing happens whenever I try to move anything between
> folders of the shared mailbox itself, while logged in with my user. I can
> move messages inside my own mailbox just fine.

I don't know about the specific errors emitted, but I've encountered the same behavior.  As it turns out, the required behavior per RFC 6851 Section 4.2 is that the message cannot be MOVE'd without the expunge permission:

4.2.  RFC 4314, Access Control List (ACL)

   The ACL rights [RFC4314] required for MOVE and UID MOVE are the union
   of the ACL rights required for UID STORE, UID COPY, and UID EXPUNGE.

You should be able to get the old behavior back by overriding the CAPABILITY response in the dovecot configuration to exclude "MOVE".

Hope that helps.

V/r,
James Cassell