OK, gurus, I've spent the last 2 days crawling through all of the posts and web postings regarding shared folders, and I simply cannot get it to work. I'm sure that there is something simple that I've overlooked, but cannot for the life of me see it :)

Here's my current config:

    # 2.2.9: /etc/dovecot/dovecot.conf
    # OS: Linux 3.16.0-46-generic x86_64 Ubuntu 14.04.3 LTS xfs
    auth_mechanisms = plain login
    debug_log_path = /var/log/debug.log
    listen = *
    mail_gid = mail
    mail_location =
    mdbox:/mail/data/private/%n:INDEX=/mail/index/private/%n
    mail_plugins = acl notify mail_log stats
    mail_privileged_group = mail
    namespace {
       list = children
       location =
    mdbox:/mail/data/shared/%%n:INDEXPVT=/mail/index/private/%n/shared_indices/%%n
       prefix = Shared/%%n/
       separator = /
       subscriptions = no
       type = shared
    }
    namespace inbox {
       inbox = yes
       location =
       mailbox Drafts {
         special_use = \Drafts
       }
       mailbox Junk {
         special_use = \Junk
       }
       mailbox Sent {
         special_use = \Sent
       }
       mailbox "Sent Messages" {
         special_use = \Sent
       }
       mailbox Trash {
         special_use = \Trash
       }
       prefix =
       separator = /
       type = private
    }
    passdb {
       args = /etc/dovecot/dovecot-ldap.conf.ext
       driver = ldap
    }
    plugin {
       acl = vfile
       acl_shared_dict = file:/mail/dict/shared-mailboxes
       autocreate = Trash
       autocreate2 = Spam
       autocreate3 = Drafts
       autocreate4 = Junk
       autosubscribe = Trash
       autosubscribe2 = Spam
       autosubscribe3 = Drafts
       autosubscribe4 = Junk
       mail_log_events = delete undelete expunge copy mailbox_delete
    mailbox_rename flag_change append
       mail_log_fields = uid box msgid size subject
       stats_refresh = 30 secs
       stats_track_cmds = yes
    }
    protocols = " imap lmtp"
    service auth {
       unix_listener /var/spool/postfix/private/auth {
         user = postfix
       }
    }
    service dict {
       unix_listener dict {
         group = mail
         mode = 0600
         user = root
       }
    }
    service imap-login {
       process_min_avail = 5
       service_count = 0
    }
    service imap {
       process_limit = 4096
    }
    service lmtp {
       unix_listener /var/spool/postfix/private/dovecot-lmtp {
         group = postfix
         mode = 0600
         user = postfix
       }
    }
    service stats {
       fifo_listener stats-mail {
         group = mail
         mode = 0660
         user = root
       }
    }
    ssl_ca = </etc/dovecot/thawte2.crt
    ssl_cert = </etc/dovecot/dovecot2.pem
    ssl_key = </etc/dovecot/private/solaray-sunglasses.com.key
    userdb {
       args = /etc/dovecot/dovecot-ldap.conf.ext
       driver = ldap
    }
    protocol lmtp {
       postmaster_address = postmaster@solaray-sunglasses.com
    }
    protocol imap {
       mail_plugins = acl notify mail_log stats imap_acl imap_stats
    }

All of our users are "real" (no virtual users or domains) and only a single domain supported. We have a user, rself, that is attempting to share his inbox with a few others that also need access to it. So the corresponding ACL files:

    root@srv56:/mail/data/shared/rself# ls -la /mail/data/shared/rself/
    total 20
    drwx------  4 rself mail    79 Aug 24 15:22 .
    drwxrwx---  7 mail  mail    71 Aug 24 16:01 ..
    -rw-------  1 rself mail    17 Aug 24 15:22 dovecot-acl-list
    drwx------ 10 rself mail   130 Aug 24 12:28 mailboxes
    drwx------  2 rself mail 12288 Aug 25 16:25 storage
    -rw-------  1 rself mail    70 Aug 24 12:28 subscriptions

And the contents of dovecot-acl-list:

    root@srv56:/mail/data/shared/rself# cat dovecot-acl-list
    1440447778 INBOX
    root@srv56:/mail/data/shared/rself#

And the mailbox-specific files:

    root@srv56:/mail/data/shared/rself/mailboxes/INBOX/dbox-Mails#
    ls -la
    total 4
    drwx------ 2 rself mail 24 Aug 25 08:16 .
    drwx------ 3 rself mail 23 Aug 24 12:28 ..
    -rw------- 1 rself mail 24 Aug 24 15:22 dovecot-acl
    root@srv56:/mail/data/shared/rself/mailboxes/INBOX/dbox-Mails#

Content:

    root@srv56:/mail/data/shared/rself/mailboxes/INBOX/dbox-Mails#
    cat dovecot-acl
    user=musrey akxeilprwts
    root@srv56:/mail/data/shared/rself/mailboxes/INBOX/dbox-Mails#

Now, the global ACL dictionary (just a flat file, not enough users to justify SQL :)

    root@srv56:~# ls -la /mail/dict/
    total 12
    drwxrwxr-x 2 root  mail 4096 Aug 24 18:05 .
    drwxr-xr-x 5 root  root 4096 Aug 23 08:51 ..
    -rw-r--r-- 1 rself mail   40 Aug 24 18:05 shared-mailboxes

And contents:

    root@srv56:~# cat /mail/dict/shared-mailboxes
    shared/shared-boxes/user/musrey/rself
    1
    root@srv56:~#

So, as far as I can tell from my RTFM activities, I think the configuration is correct. Now, I go to attempt to check the ACL using doveadm, and I get this:

    root@srv56:~# doveadm acl debug -u musrey Shared/rself/INBOX
    doveadm(musrey): Error: Can't open mailbox Shared/rself/INBOX:
    Mailbox doesn't exist: Shared/rself/INBOX
    root@srv56:~#

WTH, over? So, not thinking this is an ACL issue, but simply a namespace issue - either I have the shared namespace configured incorrectly, or I'm using it incorrectly in attempting to identify rself's INBOX when trying to verify that the ACL is working. So, I thought to myself, let's try a mailbox list, so I executed

    root@srv56:~# doveadm mailbox list -u musrey
    ACT!
    ACT!/General
    AES Outdoors
    AES Outdoors/Christy
    AES Outdoors/Gwen
    .... (many, many mailboxes in here - I should probably eliminate
    some of them :)
    VMWare
    Watchguard
    Xata Corporation
    Xata Corporation/Mike Brossman
    Xata Corporation/Mike Uremovich
    INBOX
    root@srv56:~#

But no "Shared" or "rself" to be found.

Help, please. I'm quickly going bald over this one.

--

*Mark Usrey* Director of Information Technologies

*Solaray LLC Solaray LLC* 620 S. Linden Sapulpa, Ok 74066 (918) 227-0722 Ext. 527