[Imap-protocol] Namespace separators

[Timo Sirainen]

On Wed, 2007-06-27 at 12:01 -0700, Mark Crispin wrote:
> On Wed, 27 Jun 2007, Timo Sirainen wrote:
> >> Any server that automatically lists all other users' mailboxes by default
> >> has huge privacy problem.
> > Not by default. I meant it lists all mailboxes where the mailbox owner
> > has given permission with ACLs (so filesystem permissions won't be
> > enough).
> 
> That isn't enough.  Most organizations consider it to be a privacy and 
> security violation to reveal the identities of other users.  There isn't 
> any ACL that applies to the userid space.

Only those users are visible to me who have shared a mailbox to me with
a +l ACL right.

> What's more, you're presuming that "shared mailboxes" is a small enough 
> set of names that is reasonable to list by default.  Suppose this is a 
> university, and every class list is in shared mailboxes.  What if your 
> client is accessed over wireless, or from a third world country in which 
> the user pays by the KB?

How's it any different from having a client show all of a separate
shared mailboxes namespace? Bad clients behave badly no matter what. :)

> > Actually it looks like Cyrus is doing exactly what I was going to:
> >
> > 1 namespace
> > * NAMESPACE (("" "/")) (("Other Users/" "/")) (("Shared Folders/" "/"))
> > 1 OK Completed
> > 2 list "" *
> > * LIST (\Noinferiors) "/" "INBOX"
> > * LIST (\HasNoChildren) "/" "Other Users/foo/support"
> > 2 OK Completed (0.000 secs 10 calls)
> 
> That is a design misfeature in Cyrus.  A server which does that doesn't 
> have namespaces.  It's apparently just using the NAMESPACE extension to 
> give a clue as to how to access those mailboxes in the default namespace.

Unfortunately this is the only way that works with all clients.

> > There you have a LIST that lists multiple namespaces. Do you consider
> > this bad as well?
> 
> Yes, this is bad; although not as bad as mashing multiple namespaces with 
> different hierarchy semantics together which is what you were talking 
> about earlier.
> 
> The bad thing is that it means that I, as the user, can not create a 
> personal hierarchy called "Other Users" or "Shared Folders" that have 
> entirely different purposes.  For some reason, undisclosed to my client 
> that does not do NAMESPACE, these name are stolen from me, and I as the 
> user will be surprised when bad things happen.

What if instead of calling it "Shared Folders" it was called "#shared"
but still listed with LIST?

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