Form submits but mail does not arrive

Just started using your software and have followed all relevant tutorials ( I hope). Simply trying to email a test form using UE after building form with FB.
Email is not arriving. I have tried a few variations in the mail object properties (SMTP). I know this ISP accepts PHP mail() as I have used before so I have tried to leave SMTP blank but also mail.ourdomain.com. Neither has worked. I have also tried different "triggers" - the actual submit and "any form post" I see that when click on the lightning icon there are two groups of fields to expand (1 for what looks like client side and the other server side validated entries). I have tried both submit fields..
Once I hit the submit button the contactthanks.php file is loaded ok but no email arrives.
As per Ray Borduins posting 04-14-09 "Advice on how to setup Universal Email settings " I added to mail_PHP.php:
var_dump($mailObj);
die();
after
$mailObj = mail($mailTo,$mailSubject,$mailContent,$mailHeader );

Browser returned "bool(false)" which I guess means email was NOT successfully sent to my SMTP server.

Please see attached files zipped.
Thanks