I did locate the setting. and it did bring my spam score down from 5.3 to 0.1 but ultimately it was reverse DNS that was causing the gmail spam issues.
for anyone else using smtp to send, wanting to prevent higher scoring from causing spam detection. there are 2 fields
name and host are located in the below file
/library/Zend/Mail/Protocol/Smtp.php Line 81: protected $_name = 'localhost'; change to whatever your hostname of xenforo bb is
/library/Zend/Mail/Protocol/Smtp.php Line 118: public function __construct($host = '127.0.0.1', Array $config = array()) change 127.0.0.1 to ip of your xenforo instance
some smtp servers will not allow you to be above 5.5-6 so that leaves one keyword that kicks up score 1 point and your email is DOA.