Email Services: Filter and Sort with Sieve

Our first step is to edit:

vim /etc/dovecot/conf.d/15-lda.conf

Find the protocol lda section and ensure it looks like this:

protocol lda {
  # Space separated list of plugins to load (default is global mail_plugins).
  mail_plugins = sieve
}

Now configure postfix:

vim /etc/postfix/main.cf 

Find the mailbox_command setting and set it to use the dovecot specific delivery binary:

mailbox_command = /usr/libexec/dovecot/deliver

Install Sieve:

yum install dovecot-pigeonhole -y

vim /etc/dovecot/conf.d/90-plugin.conf

Set the plugin up like so:

plugin {
  # setting_name = value
    sieve=~/.dovecot.sieve
    sieve_dir = ~/sieve
    sieve_global_dir = /home/sieve
    sieve_max_script_size = 1M
}

Now we need to edit dovecot's config again:

vim /etc/dovecot/dovecot.conf

The protocols line should include the sieve plugin:

protocols = imap sieve

Edit the 20-managesieve.conf file and uncomment the following lines:

vim /etc/dovecot/conf.d/20-managesieve.conf

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

Now we can build our Sieve script:

vim /home/test_user/.dovecot.sieve

Your script should look something like this:

require "fileinto";

if header :contains "Subject" "WORK" {
        fileinto "Work";
}

Restart postfix and dovecot:

systemctl restart postfix
systemctl restart dovecot

Sieve is configured!

1. To test your sieve script, you should send a test email.

telnet localhost 25
Trying ::1...
Connected to localhost.
Escape character is '^]'.
220 server1.example.com ESMTP Postfix
ehlo localhost
250-server1.example.com
250-PIPELINING
250-SIZE 10240000
250-VRFY
250-ETRN
250-ENHANCEDSTATUSCODES
250-8BITMIME
250 DSN
mail from: [email protected]
250 2.1.0 Ok
rcpt to: [email protected]
250 2.1.5 Ok
data
354 End data with <CR><LF>.<CR><LF>
Subject: WORK
.
250 2.0.0 Ok: queued as 3CA4197CBF

2. Once sent, copy the message ID (the number after "queued as" above) and use it to grep the mail log:

[root@server1 test_user]# grep 3CA4197CBF /var/log/maillog
Jun  8 06:22:53 server1 postfix/smtpd[12092]: 3CA4197CBF: client=localhost[::1]
Jun  8 06:22:59 server1 postfix/cleanup[12096]: 3CA4197CBF: message-id=<[email protected]>
Jun  8 06:22:59 server1 postfix/qmgr[1670]: 3CA4197CBF: from=<[email protected]>, size=323, nrcpt=1 (queue active)
Jun  8 06:22:59 server1 dovecot: lda(test_user): sieve: msgid=<[email protected]>: stored mail into mailbox 'Work'
Jun  8 06:22:59 server1 postfix/local[12097]: 3CA4197CBF: to=<[email protected]>, relay=local, delay=16, delays=16/0.01/0/0.08, dsn=2.0.0, status=sent (delivered to command: /usr/libexec/dovecot/deliver)
Jun  8 06:22:59 server1 postfix/qmgr[1670]: 3CA4197CBF: removed

As you can see, the 4th line indicates that Sieve sorted the email into the correct folder. Congratulations!