[Dovecot] workaround for shared maildirs

[Giuliano Gavazzi]

Hello, this is my first post to the list.
I have several mailservers running courier-imap, but am planning to  
convert one (and maybe more) to dovecot 1.1.4. In the process I am  
also looking to finally implement shared maildirs.
As it is well known some clients (notable Apple's Mail) have problems  
in showing shared folders if  the correct private namespace (INBOX) is  
set in the client, as only folders beneath the INBOX root are displayed.
I have seen some solutions proposed, but none satisfactory.

As the problem stems in the invisibility of secondary namespaces from  
Mail.app, I though that tricking the namespace prefix to push the  
shared mailboxes inside the private INBOX namespace could be a  
solution and tried the following:

namespace public {
    separator = .
    prefix = INBOX.Public.
    inbox = no
    location = maildir:/SharedMaildirs/Public:CONTROL=~/Maildir/ 
control/Public:INDEX=~/Maildir/index/Public
    hidden = yes
    list = yes
    subscriptions = yes
}

note the bogus INBOX.Public prefix.

Note also that CONTROL might be better not set as this is a Maildir  
(see Keyword sharing in http://wiki.dovecot.org/SharedMailboxes)

Initially I had defined an additional public namespace with the same  
maildir and a normal prefix, but this seems not necessary.

Well, after some tests from Thunderbird, Mail and cone (yes, the  
courier UA) I can say it works . Still have to check Outlook and  
Opera, but this is encouraging.

As the public namespace Public is actually contained inside the  
private (INBOX), as if it was a private mailbox (with no messages)  
called Public, it is actually possible to create such a mailbox inside  
INBOX and end up with a private mailbox called Public containing  
private messages AND public mailboxes... Any mailbox that a user  
creats inside Public instead, will end up being a public mailbox as  
expected.

Thanks or any comments.

Giuliano