Email class SMTP Auth

[eluser]toymachiner62[/eluser]
[quote author="piker" date="1228120019"]

Documentation do not explain smtp authentication. Why ?

$config['protocol'] = "smtp";
$config['_smtp_auth'] = TRUE;[/quote]

I too am also curious why this is not mentioned. I spent 3 days trying to figure it out and ended up using PHPMailer.