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Track user last login time

Dovecot ships a last_login plugin since Dovecot-2.2.14, it can be used to easily save and update user's last-login timestamp in SQL database.

Currently this plugin works with MySQL/MariaDB, but not PostgreSQL.

It works on:

• CentOS 7 (Dovecot-2.2.36), 8 (Dovecot-2.2.36)
• Debian 9 (Dovecot-2.2.27)
• Ubuntu 16.04 (Dovecot-2.2.22)
• Ubuntu 18.04 (Dovecot-2.2.33)
• OpenBSD 6.4 (Dovecot-2.2.36), 6.5, 6.6
• FreeBSD (Dovecot-2.3.x in ports tree)

Create required SQL table to store last login info

We need to create a sql table to store the user last login info.

• For MySQL/MariaDB backends, we create the sql table in database vmail.
• For OpenLDAP backend, since it doesn't have vmail SQL database, so we create it in iredadmin instead, it will be easier for iRedAdmin(-Pro) to read this info.

SQL statement:

CREATE TABLE IF NOT EXISTS `last_login` (
    `username` VARCHAR(255) NOT NULL DEFAULT '',
    `domain` VARCHAR(255) NOT NULL DEFAULT '',
    `imap` INT(11) DEFAULT NULL,
    `pop3` INT(11) DEFAULT NULL,
    `lda` INT(11) DEFAULT NULL,
    PRIMARY KEY (`username`),
    INDEX (`domain`),
    INDEX (`imap`),
    INDEX (`pop3`),
    INDEX (`lda`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

Configure Dovecot

Open Dovecot config file /etc/dovecot/dovecot.conf (Linux/OpenBSD) or /usr/local/etc/dovecot/dovecot.conf (FreeBSD), enable last_login plugin for POP3 and IMAP services by appending plugin name to its mail_plugins parameter like below, and add extra required settings. Note: we use ... below as a placeholder for your existing settings.

protocol lda {
    # Append plugin name `last_login` here
    mail_plugins = ... last_login
    ...
}

protocol lmtp {
    # Append plugin name `last_login` here
    mail_plugins = ... last_login
    ...
}

protocol imap {
    # Append plugin name `last_login` here
    mail_plugins = ... last_login
    ...
}

protocol pop3 {
    # Append plugin name `last_login` here
    mail_plugins = ... last_login
    ...
}

dict {
    ...

    # Add this line. For FreeBSD, please replace the path by
    # /usr/local/etc/dovecot/dovecot-last-login.conf
    lastlogin = mysql:/etc/dovecot/dovecot-last-login.conf
}

plugin {
    ...

    # Add 2 lines
    last_login_dict = proxy::lastlogin
    last_login_key = last-login/%s/%u/%d
}

Create file /etc/dovecot/dovecot-last-login.conf (Linux/OpenBSD) or /usr/local/etc/dovecot/dovecot-last-login.conf (FreeBSD) with content below:

connect = host=127.0.0.1 port=3306 dbname=vmail user=vmailadmin password=my_secret_password

map {
    pattern = shared/last-login/imap/$user/$domain
    table = last_login
    value_field = imap
    value_type = uint

    fields {
        username = $user
        domain = $domain
    }
}

map {
    pattern = shared/last-login/pop3/$user/$domain
    table = last_login
    value_field = pop3
    value_type = uint

    fields {
        username = $user
        domain = $domain
    }
}

# Track the time of last email delivered to mailbox via LDA.
# Please enable `last_login` plugin in the `protocol lda {}` block in dovecot.conf.
map {
    pattern = shared/last-login/lda/$user/$domain
    table = last_login
    value_field = lda
    value_type = uint

    fields {
        username = $user
        domain = $domain
    }
}

# Track the time of last email delivered to mailbox via LMTP,
# Please enable `last_login` plugin in the `protocol lmtp {}` block in dovecot.conf.
# We treat lmtp as lda, store the time in sql column `lda`.
map {
    pattern = shared/last-login/lmtp/$user/$domain
    table = last_login
    value_field = lda
    value_type = uint

    fields {
        username = $user
        domain = $domain
    }
}

Since this file contain SQL username and password, we must protect it with proper owner/group and permission (we use Linux/BSD for example below):

chown dovecot:dovecot /etc/dovecot/dovecot-last-login.conf
chmod 0400 /etc/dovecot/dovecot-last-login.conf

Now it's ok to restart Dovecot service.

Test

After restarted Dovecot service, please monitor its log file /var/log/dovecot/dovecot.log, if there's something wrong, Dovecot will log the error message to this file.

Try to access your mailbox with webmail or MUA like Outlook/Thunderbird, you should see the time has been updated in SQL table vmail.last_login (MySQL/MariaDB backends) or iredadmin.last_login (OpenLDAP backend). For example:

sql> USE vmail;
sql> SELECT * FROM last_login;
+-----------------+--------+------------+------+------+
| username        | domain | imap       | pop3 | lda  |
+-----------------+--------+------------+------+------+
| postmaster@a.io | a.io   | 1554172329 | NULL | NULL |
+-----------------+--------+------------+------+------+
1 row in set (0.01 sec)

References

• Dovecot plugin: last_login