Dovecot-extras

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dovecot-extras for SME Server

	Skill level: easy
	The instructions on this page can be followed by a beginner.

Maintainer

Daniel B. from Firewall Services

Description

dovecot-extras is a contrib to bring 'sieve' support and IMAP acl (sharedmailbox) to dovecot, the imap server

• Shared Mailboxes and IMAP ACL: this feature enables sharing of mail folders between users using IMAP ACL. See http://wiki2.dovecot.org/ACL and http://wiki2.dovecot.org/SharedMailboxes
• Sieve scripts and manage sieve daemon: this feature adds sieve scripts support. Sieve is a script language for server side mail processing when mails arrive in your mailbox. With this, you can create filters, reject mails with a custom message, configure a vacation message, forward some mails etc…. These features are often also available on mail clients (Outlook, Thunderbird, Evolution etc…) but the advantage of using sieve is that everything is processed on server side, as soon as the mail arrive in your INBOX, which means everything will work even if your client is not running. See http://wiki2.dovecot.org/Pigeonhole

Requirements

You need the firewall-services repo to install this contribs

Installation 9.x Only

This contrib is currently held in the fws repository, so the following commands will install on your smeserver.

yum install --enablerepo=fws smeserver-dovecot-extras

You will then need to activate the database changes etc. The 'official' way is to perform

signal-event post-upgrade;  signal-event reboot

or if you do not want to restart your computer

signal-event email-update

Configuration

Sieve

There is no panel in the server-manager, You have to use the db command

[root@sme9 ~]# config show sieve 
 sieve=service
   TCPPort=4190
   access=private
   status=enabled

for example

config setprop sieve TCPORT 5190
signal-event email-update

• IP listening

you can change the IP listening (default localhost)

config setprop sieve Listen xxx.xxx.xxx.xxx
signal-event email-update

• Sieve and dovecot-lda

When Sieve is enabled, dovecot-lda is used to deliver mail in mailboxes (so it can apply sieve scripts) instead of qmail. Dovecot-lda is more ressources intensives than qmail, so you may have performance penalty when users receive a lot of mails (for example, when you use the Bcc qpsmtpd's plugin to copy every mail in one mailbox). You can selectivly disable dovecot-lda for some users, for example, to disable dovecot-lda for user maillog:

db accounts setprop maillog Sieve disabled
signal-event email-update

This will let qmail handle mail delivery for this user.

• Sieve and existing procmail / maildrop rules

If smeserver-mailsorting is installed in addition to this contrib, filter rules defined in a user's ~/.procmailrc or ~/.mailfilter file are applied prior to the mail getting passed to dovecot-lda and Sieve.

Shared Mailboxes

ShareMailbox is an important feature.

To enable it:

db configuration setprop dovecot SharedMailbox enabled
signal-event email-update

When this feature is enabled, a special group named sharedmailbox (automatically created during install) will have:

• x permission on each user home (/home/e-smith/files/users/username) in order to access the Maildir folder (but it won't have any permission to read something else, like the home sub-folder)
• Full read / write access to the Maildir for everyone

This special group is empty (no member), so this has limited impact on the security of the server. Just be sure to never add any user in this group. (It's a system group, and won't appear in the server-manager, so you cannot add members easily).

When a user access its mailbox through the IMAP server, dovecot spawn a new process with the standard user privileges, plus the sharedmailbox group. So basically a user is member of this special group only through dovecot. This configuration allows shared mailbox at the filesystem level. Effective permissions between differents users are enforced by IMAP ACL extension. You need a client which support this (tested with SOGo and Thunderbird using this extension ).

Once enabled, you can grant different access level (read, post, delete, change flags, create sub folders etc.) to other users, or group of users on your IMAP folders.

Uninstall

yum remove smeserver-dovecot-extras
signal-event post-upgrade;  signal-event reboot

Bugs

Sources for this contribs can be found in Firewall Service's repository [1]