html - Using PHP's mail() - name.com hosting issue -

my site hosted on name.com, , test uploaded simple file called contact.php @ top.

<?php  $to = '~~~~'; $subject = 'enquiry '; $name = $_post['name']; $email - $_post['email']; $message = $_post['message'];  if ($_post){ mail($to, $subject, $message, $header); $feedback = "sent"; } ?> 

so, when click submit button sends mail. inside p tag have echo $feedback, shows after click submit.

the mail not send? i'm doing wrong here, or need configure cpanel in way?

since header optional , left undefined, removing should resolve issue.