Sieve interpreter & Dovecot ManageSieve

September 17, 2023 Roberto Puzzanghera 56 comments

The Pigeonhole project provides Sieve support as a plugin for Dovecot's Local Delivery Agent (LDA) and also for its LMTP service. The plugin implements a Sieve interpreter, which filters incoming messages using a script specified in the Sieve language. The Sieve script is provided by the user and, using that Sieve script, the user can customize how incoming messages are handled. Messages can be delivered to specific folders, forwarded, rejected, discarded, etc.

Dovecot Managesieve Server is a service used to manage a user's Sieve script collection.

Info: http://pigeonhole.dovecot.org/ - https://doc.dovecot.org/configuration_manual/sieve/
Version: 0.5.21
Download: http://pigeonhole.dovecot.org/download.html

If you want to support filters in your email you have to manage the Sieve rules by means of the dovecot-pigeonhole server. When you create a filter with your webmail or email client, you write a Sieve script to customize how messages are delivered, e.g. whether they are forwarded, rejected or stored in special folders. But, in order to do so, Dovecot must also act as a Local Delivery Agent in place of vpopmail/vdelivermail, e.g. it must be Dovecot to store the email messages in the users' Maildirs. This guide will try to show how to accomplish this.

Install as follows:

PIGEONHOLE_VER=0.5.21
cd /usr/local/src
wget https://pigeonhole.dovecot.org/releases/2.3/dovecot-2.3-pigeonhole-${PIGEONHOLE_VER}.tar.gz
tar xzf dovecot-2.3-pigeonhole-${PIGEONHOLE_VER}.tar.gz
chown -R root.root dovecot-2.3-pigeonhole-${PIGEONHOLE_VER}
cd dovecot-2.3-pigeonhole-${PIGEONHOLE_VER}

# the program has to find the dovecot-config file in /usr/local/dovecot/lib/dovecot/
./configure \
        --prefix=/usr/local/dovecot-pigeonhole \
        --with-dovecot=/usr/local/dovecot/lib/dovecot/
make

If an old version of pigeonhole is already installed, delete the symbolic link before installing:

rm /usr/local/dovecot-pigeonhole

Then proceed with the installation

make install

cd /usr/local
mv /usr/local/dovecot-pigeonhole /usr/local/dovecot-2.3-pigeonhole-${PIGEONHOLE_VER}
ln -s /usr/local/dovecot-2.3-pigeonhole-${PIGEONHOLE_VER} /usr/local/dovecot-pigeonhole

Configuration

Copy the default config files in the actual config directory:

cd /usr/local/dovecot/etc/dovecot/conf.d
cp -p ../../../share/doc/dovecot/example-config/conf.d/20-managesieve.conf .
cp -p ../../../share/doc/dovecot/example-config/conf.d/90-sieve.conf .

In this way the next time you will run dovecot the two config files will be loaded.

Now enable (if not done yet) the plugin inside 15-lda.conf

protocol lda {
  mail_plugins = $mail_plugins sieve
}

and adjust the file conf.d/20-managesieve.conf to your needs. This is the file which works for me; you can find it in my tarball:

##
## ManageSieve specific settings
##

# Uncomment to enable managesieve protocol:
protocols = $protocols sieve

# Service definitions

service managesieve-login {
  inet_listener sieve {
    port = 4190
  }
}

service managesieve {
}

# Service configuration

protocol sieve {
}

Now adjust the file conf.d/90-sieve.conf. This works for me (you have this file in your config directory if you have downloaded my tarball):

##
## Settings for the Sieve interpreter
##

# Do not forget to enable the Sieve plugin in 15-lda.conf and 20-lmtp.conf
# by adding it to the respective mail_plugins= settings.

plugin {
 sieve = file:~/.sieve;active=~/.sieve/dovecot.sieve
 sieve_before = /usr/local/dovecot/etc/dovecot/sieve/
 sieve_extensions = +notify +imapflags +spamtest
}

Now restart dovecot

dovecotctl restart

Adjusting `dot-qmail` files to enable `Dovecot LDA` and `Sieve`

Read this for more information on how the dot-qmail files work.

If you want to use the sieve rules your delivery agent has to be Dovecot-LDA. This can be accomplished enabling Dovecot-LDA in the dot-qmail file which has to handle the delivery in this way:

|/var/qmail/bin/preline -f /usr/local/dovecot/libexec/dovecot/deliver -d $EXT@$USER

But you may want to have control over qmail forwards as well, which needs the vpopmail's vdelivermail delivery. The trick is to have vdelivermail in the domain's .qmail-default, which will eventually handle the forwards, and Dovecot-LDA in each users' .qmail file, which will be responsible for the final storing of the email and for the sieve filters. If you have patched vpopmail with my combined patch and configured it with --enable-defaultdelivery the dot-qmail files will be managed by vpopmail according to this logic. Read this page for detailed informations.

Setting up an anti spam sieve rule

Info:

If you decided to let simscan pass through the spam with a score below spam_hits (qmail/control/simcontrol file), you may want to store them in the Junk folder. In this case Managesieve server will execute a script before processing the user's script so that all spam messages will be discarded or moved into junk and all the other rules ignored.

First of all create a folder where to store your global scripts and assign the write priviledges to the vpopmail user:

cd /usr/local/dovecot/etc
mkdir sieve
chown -R vpopmail.vchkpw sieve

Modify conf.d/90-sieve.conf to enable the required sieve extensions and load the script that you want to execute before:

sieve_extensions = +spamtest +spamtestplus +relational +comparator-i;ascii-numeric
sieve_before = /usr/local/dovecot/etc/sieve/

Now create the script /usr/local/dovecot/etc/sieve/move-spam.sieve (.sieve extension otherwise it will be ignored):

require ["fileinto"];
if anyof (header :contains "X-Spam-Flag" "YES")
{
 fileinto "Junk";
}
/* Other messages get filed into INBOX */

Every time you modify the global files you have to pre-compile them using the sievec program (more info here):

su vpopmail
cd /usr/local/dovecot/etc/sieve
/usr/local/dovecot-pigeonhole/bin/sievec .

Testing managesieve

First of all try to connect to the 4190 port via telnet. This is what you are going to see if the server is working:

> telnet 0 4190

Trying 0.0.0.0...
Connected to 0.
Escape character is '^]'.
"IMPLEMENTATION" "Dovecot Pigeonhole"
"SIEVE" "fileinto reject envelope encoded-character vacation subaddress comparator-i;ascii-numeric relational regex imap4flags copy include variables body enotify environment mailbox date spamtest spamtestplus"
"NOTIFY" "mailto"
"SASL" "PLAIN LOGIN CRAM-MD5"
"STARTTLS"
"VERSION" "1.0"
OK "Dovecot ready."

If you create a sieve rule by your mail client (Mozilla Thunderbird provides a special add-on here https://addons.mozilla.org/en-US/thunderbird/addon/2548/) or via webmail (read the next note concerning Roundcube webmail), this is what you should see in the log simply setting a redirect filter:

Oct 22 00:03:13 lda(test@yourdomain.net): Info: sieve: msgid=<c3445037f979a8cb793df1f858b7a4f9@somedomain.com>: forwarded to <someone@somewhere.net>

Testing

Indexing

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Comments

Error net connect

Bob August 5, 2022 21:55

I'm using this in my .qmail files:

|/var/qmail/bin/preline -f /usr/lib/dovecot/dovecot-lda -d $EXT@$USER

However, when I try to deliver mail I get this error in qmail-send:

delivery 2: deferral: lda(smtp.edm-inc.com):_Error:_net_connect_unix(/var/run/dovecot/stats-writer)_failed:_Permission_denied/

Any ideas what is causing this?

Sieve interpreter & Dovecot ManageSieve

Configuration

Adjusting dot-qmail files to enable Dovecot LDA and Sieve

Setting up an anti spam sieve rule

Testing managesieve

Comments

qmail notes

LXC scripts

Other contents

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See also...

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Adjusting `dot-qmail` files to enable `Dovecot LDA` and `Sieve`