roundcube-identity_db/config.inc.php.dist

<?php
$conf = array();

// Enables (true) or disables (false) the plugin
$conf['update_on_login'] = true;

// Remove identities for which the email address is unknown for this user
$conf['remove_unknown_identities'] = true;

// Connection to the database which holds user aliases information
$conf['dsn'] = '';

// Query all aliases for a given user. '%u' will be replaced with the username.
// Example : SELECT aliases.email FROM aliases LEFT JOIN users ON aliases.user_id=users.id WHERE users.name="%u"
$conf['identities_query'] = '';

// Finally register to the global config
$config['identity_db'] = $conf;