the line of code is the one i listed in the first email:
if ($_SESSION["eCartCheckoutForm_street2"] !="") echo "<br />";
Here is lines 273-275 (1 line before and after)
$MailBody = $MailBody . " ";
if ($_SESSION["eCartCheckoutForm_street2"] !="") echo "<br />";
$MailBody = $MailBody . "\r\n";