Patch: add new lmtptarget annotation

[Frank Richter]

Hello Stephen,

> We use shared mailboxes quite extensively for role-based communication.
> For quite some time we've had a problem with users deleting or renaming
> mailboxes into which we deliver mail. We can, and do, use IMAP ACLs to
> dissallow users from deleting the delivery target mailbox. But when a
> user creates a child mailbox it inherits the ACLs of the parent, and the
> user is then not able to delete or rename the sub folder.

This is an issue here as well. Thanks for your solution! 
Would be a good thing to see it included in an official release.

Frank

> As a fix, I have written a patch against 2.3.16 to add a new lmtptarget
> mailbox annotation. When enabled, Cyrus won't allow the mailbox to be
> deleted or renamed. We can then set whatever ACLs we want inherited by
> child mailboxes, happy in the knowledge the user won't blat the mailbox
> and cause mail to bounce.
>
> The rationale here is that Cyrus treats user.foo with special
> significance as a delivery target, but does not do the same for shared
> mailboxes because there is no way for Cyrus to know which shared
> mailboxes we intend to deliver mail into. Using a mailbox annotation
> seems a nice way of flagging this.
>
> Patch attached. Comments welcome.

-- 
E-Mail: Frank.Richter at hrz.tu-chemnitz.de  http://www.tu-chemnitz.de/~fri/
Work:   Computing Services,  Chemnitz University of Technology,  Germany