To see what the problem is, please load this script (call it something like mail_test.php), edit the $from and $to values to match your domain and your outside email and then run from the web.
PHP Code:
<?php
// TEST OF THE MAIL SYSTEM USING PHP mail()
date_default_timezone_set('America/Los_Angeles');
echo date('l jS \of F Y h:i:s A');
echo "\n";
$from = "cPanelUserName@yourwebsite.com";
$to="anEmailaccount@gmail.com";
$mailbody="Test message sent (PST): \n" . date('l jS \of F Y h:i:s A');
$subject="Test of PHP mail()" ;
$headers = "Content-type: text/plain; charset=windows-1251 \r\n";
$headers .= "From: $from\r\n";
$headers .= "Reply-To: $from\r\n";
$headers .= "MIME-Version: 1.0\r\n";
$headers .= "X-Mailer: PHP/" . phpversion();
$resp = mail($to, $subject, $mailbody, $headers);
if( $resp ){
$outcome = "Mail sent" ;
} else {
$outcome = "Mail not sent";
}
print "\nThe mail system said: $outcome\n\n" ;
exit();
?>