...
// A driver to use for password change. Default: "sql".
// See README file for list of supported driver names.
$rcmail_config['password_driver'] = 'sql';
...
// Determine whether current password is required to change password.
// Default: false.
$rcmail_config['password_confirm_current'] = true;
...
// Pour garantir des mots de passe (un peu) sécurisés
// Require the new password to be a certain length.
// set to blank to allow passwords of any length
$rcmail_config['password_minimum_length'] = 8;

// Require the new password to contain a letter and punctuation character
// Change to false to remove this check.
$rcmail_config['password_require_nonalpha'] = true;
...
// SQL Driver options
...
$rcmail_config['password_db_dsn'] = 'mysql://postfixadmin:postfixadmin-password@localhost/postfix';
...
$rcmail_config['password_query'] = 'UPDATE mailbox SET password=%c WHERE username=%u  LIMIT 1';
...
$rcmail_config['password_dovecotpw_method'] = 'CRAM-MD5';
...