From iRedMail

Mission

Enable shared folders under iRedMail with dovecot 1.2.

Requirements

• A properly working iRedMail system;
• A properly working dovecot 1.2 instead of the default 1.1;

Notes

• This article was written with a CentOS-based system in mind. Adapt it for your system.

Step-by-step configuration

• Step 1.

Add proper namespaces to dovecot.conf:

# Namespaces
namespace private {
	subscriptions = yes
	separator = /
	prefix = 
	inbox = yes
}

namespace shared {
	subscriptions = no
	separator = /
	prefix = Shared/%%u/
	location = maildir:%%Lh/Maildir:INDEX=%Lh/Maildir/Shared/%%Lu
	list = children
	hidden = no
	inbox = no
}

The private namespace is the default namespace, if it's already in the config do not add it a second time. shared is the one we need here.

• Step 2.

Add proper ACL dictionary to dict section of dovecot.conf:

dict {
    acl = mysql:/etc/dovecot-acl-shared-dict.conf
}

• Step 3.

Add ACLs to protocol imap in dovecot.conf:

protocol imap {
    [...]
    mail_plugins = quota imap_quota expire [...] acl imap_acl
    [...]
}

• Step 4.

Create the file /etc/dovecot-acl-shared-dict.conf:

connect = host=localhost dbname=vmail user=vmailadmin password=PASSWORD_HERE

map {
  pattern = shared/shared-boxes/user/$to/$from
  table = user_shares
  value_field = dummy

  fields {
    from_user = $from
    to_user = $to
  }
}