[Dovecot] Strange errors with imapc+acl in 2.2.x

[René Neumann]

Hi,

after migrating to 2.2 (currently using 2.2.5), I see strange error
messages when using imapc + public namespace + acl

My setup: I create a public shared mailbox with imapc as location. Then
I restrict this mailbox to one user only using ACLs.

This works for this one special user, but for all others an error gets
logged and they can't access their mailbox anymore:

Sep 24 18:09:46 [dovecot] imap(other at my.domain): Error: user
other at my.domain: Initialization failed: Namespace 'Gemeinsam.':
Ambiguous mail location setting, don't know what to
 do with it: yes (try prefixing it with mbox: or maildir:)

                                Sep 24 18:09:46 [dovecot]
imap(other at my.domain): Error: Invalid user settings. Refer to server log
for more information.


My config (relevant parts):

------------------ Dovecot conf ----------------

imapc_host = some_host
imapc_port = 143
imapc_user = some_user
imapc_password = some3$pwd
imapc_ssl = starttls
imapc_ssl_verify = no

namespace gemeinsam {
	type = public
	separator = .
	location = imapc:
	prefix = Gemeinsam.
	subscriptions = no
}

# I also tried different combinations of hidden and list

plugin {
	acl = vfile:/etc/dovecot/global-acls:cache_secs=300
}

------------- /etc/dovecot/global-acls/Gemeinsam -------

anyone
user=special at my.domain lrwstipekxa

--------------------------------------------------------

Does anyone have any thoughts about this?

Thanks,
René