如何在梨邮件中设置auth方法

I just need help setting the auth type in pear mail. This is the array I have currently.. auth is set to true, but I need it to be true and set to LOGIN method. Can anyone help me out with the syntax for this?

$smtp = Mail::factory('smtp', array(
        'host' => 'ssl://server.net',
        'port' => '465',
        'auth' => true,
        'timeout' => 20,
        'username' => 'theusername',
        'password' => 'thepassword'
    ));

According to https://pear.php.net/manual/en/package.mail.mail.factory.php#9454 you should set the auth field to "LOGIN" and not just true.