Mailbox sharing, user to user in same domain, OK! User to user sharing in separate domains, problem. ( ... and more oh boy!)

22 Jul 2020


      Dovecot -n and version present at the bottom of the email for
legibility.
System is a Debian 10 + Virtualmin hosting setup for my domains
Hello everyone, my first post. Sorry for the long and confusing post,
I'm pretty new to dovecot other than basic functionality.
I recently in the last week went through the documentation for both
shared (user to user) and public mailboxes and got them both working.
Took me a bit but eventually I figured it out, but I am still
encountering some stubborn scenarios.
I am having some issues with 2 types of sharing. ( I believe problem A +
B are related as the error is similarly permission based error)
For inconsistencies in the user account names,  user@domain.com vs
user-domain.com please see issue C, which my workaround is functional.
A.)
Sharing user to user between in the same domain works fine.
Sharing user to user in different domains gives me some permission
errors.
Permissions have been granted (to (using Linux ACL for more fine grained
permissions) as far as I can tell.
Trying to share the info "INBOX" (fullshare, same issue for single boxes
as well) from the info@primarydomain.com to user@externaldomain.com
from info@primarydomain.com Mailder
cat dovecot-acl
user=user-externaldomain.com akxeilprwts
getfacl dovecot-acl
# file: dovecot-acl
# owner: info@primarydomain.com
# group: primarydomain.com
user::rw-
user:user@externaldomain.com:rwx    #effective:rw-
user:info@primarydomain.com:rwx           #effective:rw-
group::---
mask::rw-
other::---
doveadm acl debug -u user-externaldomain.com
"@/info@primarydomain.com/INBOX"
doveadm(user-externaldomain.com): Error:
stat(/home/primarydomain.com/homes/info/Maildir/tmp) failed: Permission
denied (euid=1121(user@externaldomain.com) egid=1091(holanow.com)
missing +x perm: /home/primarydomain.com, we're not in group
1092(primarydomain.com), dir owned by 1126:1092 mode=0750)
doveadm(user-externaldomain.com): Error: Can't open mailbox
@/info@primarydomain.com/INBOX:
stat(/home/primarydomain.com/homes/info/Maildir/tmp) failed: Permission
denied (euid=1121(user@externaldomain.com) egid=1091(holanow.com)
missing +x perm: /home/primarydomain.com, we're not in group
1092(primarydomain.com), dir owned by 1126:1092 mode=0750)
getfacl /home/primarydomain.com/homes/info/Maildir/tmp
# file: home/primarydomain.com/homes/info/Maildir/tmp
# owner: info@primarydomain.com
# group: primarydomain.com
user::rwx
user:user@externaldomain.com:rwx
user:info@primarydomain.com:rwx
group::---
mask::rwx
other::---
default:user::rwx
default:user:user@externaldomain.com:rwx
default:user:info@primarydomain.com:rwx
default:group::---
default:mask::rwx
default:other::---
getfacl /home/primarydomain.com/homes/info/Maildir
# file: home/primarydomain.com/homes/info/Maildir/
# owner: info@primarydomain.com
# group: primarydomain.com
user::rwx
user:user@externaldomain.com:rwx
user:info@primarydomain.com:rwx
group::---
mask::rwx
other::---
default:user::rwx
default:user:user@externaldomain.com:rwx
default:user:info@primarydomain.com:rwx
default:group::---
default:mask::rwx
default:other::---
B.)
Public mailbox, mailboxes that are physically present on the public mail
dir, work fine.
Public boxes which are symlinks to mailboxes to other users, with
correct permission and ACL, always give me permission errors and do not
show up publicly.
These type of mailboxes do show up if the person already has user to
user share setup with those boxes, which due to problem A, means only
within the same domain.
Similar errors as to the A scenario, even if giving complete rwx access
to all (user/group/other) I still get permission denied issues.
It just feel like dovecot isn't even trying to access the files
C. Tiny "other" problem I have worked around already.
dovecot-acl when using users via their user@domain.com account doesn't
lookup the user correctly.
I already have set,
auth_username_translation = @-
which works for when users login but it doesn't seem to work with
dovecot-acl files.
I have helper account pointers replacing the @ with - and then the ACL
file works fine.
Would prefer acl files contain,
user=user1@primarydomain.com akxeilprwts
user=user2@primarydomain.com akxeilprwts
But this works and is not a show stopper.
user=user1-primarydomain.com akxeilprwts
user=user2-primarydomain.com akxeilprwts

dovecot --version
2.3.4.1 (f79e8e7e4)
# 2.3.4.1 (f79e8e7e4): /etc/dovecot/dovecot.conf
# Pigeonhole version 0.5.4 ()
# OS: Linux 5.4.44-2-pve x86_64 Debian 10.4
# Hostname: vps1.abclution.com
doveconf: Warning: please set ssl_dh= /etc/dovecot/dh.pem
auth_mechanisms = plain login
auth_username_translation = @-
mail_debug = yes
mail_location = maildir:~/Maildir
mail_plugins = acl
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 = /
}
namespace public_ns1 {
location =
maildir:/home/.Public_Mailboxes:INDEX=~/Maildir/public_ns1:INDEXPVT=~/Maildir/public_ns1
prefix = Public/
separator = /
subscriptions = no
type = public
}
namespace shared_ns1 {
list = yes
location =
maildir:%%h/Maildir:INDEX=~/Maildir/shared_ns1/%%u:INDEXPVT=~/Maildir/shared_ns1/%%u
prefix = @/%%u/
separator = /
subscriptions = no
type = shared
}
passdb {
driver = pam
}
plugin {
acl = vfile
acl_anyone = allow
acl_defaults_from_inbox = yes
acl_shared_dict = file:%h/Maildir/shared-mailboxes
}
protocols = " imap pop3"
service auth {
unix_listener auth-userdb {
mode = 0777
}
}
ssl_cert =

Andreas T (DC)

Dovecot -n and version present at the bottom of the email for legibility. System is a Debian 10 + Virtualmin hosting setup for my domains

Andreas T (DC)

Dovecot -n and version present at the bottom of the email for legibility. System is a Debian 10 + Virtualmin hosting setup for my domains

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