PHP Mail form not receiving -

i use have email form using php. seems stopped working , can't find working script. claims email got sent never receive it.

i've tried both yahoo , gmail accounts accounts on server. maybe there wrong code? feel it's not making sense there doesn't seem solution anywhere.

thank you.

   <?php     if(isset($_post['email'])) {      $email_to = "somemail@someserver.com";     $email_subject = "your email subject line";       function died($error) {       echo "we sorry, there error(s) found form submitted. ";      echo "these errors appear below.<br /><br />";      echo $error."<br /><br />";      echo "please go , fix these errors.<br /><br />";      die();     }    // validation expected data exists  if(!isset($_post['first_name']) ||      !isset($_post['last_name']) ||      !isset($_post['email']) ||      !isset($_post['telephone']) ||      !isset($_post['comments'])) {      died('we sorry, there appears problem form submitted.');         }      $first_name = $_post['first_name'];     $last_name = $_post['last_name'];     $email_from = $_post['email'];     $comments = $_post['comments'];    $error_message = "";  $email_exp = '/^[a-za-z0-9._%-]+@[a-za-z0-9.-]+\.[a-za-z]{2,4}$/';    if(!preg_match($email_exp,$email_from)) {    $error_message .= 'the email address entered not appear valid.<br />';       }     $string_exp = "/^[a-za-z .'-]+$/";     if(!preg_match($string_exp,$first_name)) {    $error_message .= 'the first name entered not appear valid.<br />';       }      if(!preg_match($string_exp,$last_name)) {     $error_message .= 'the last name entered not appear valid.<br />';    }    if(strlen($comments) < 2) {      $error_message .= 'the comments entered not appear valid.<br />';    }    if(strlen($error_message) > 0) {      died($error_message);    }      $email_message = "form details below.\n\n";        function clean_string($string) {       $bad = array("content-type","bcc:","to:","cc:","href");        return str_replace($bad,"",$string);      }        $email_message .= "first name: ".clean_string($first_name)."\n";      $email_message .= "last name: ".clean_string($last_name)."\n";      $email_message .= "email: ".clean_string($email_from)."\n";      $email_message .= "comments: ".clean_string($comments)."\n";        $headers = 'from: '.$email_from."\r\n".      'reply-to: '.$email_from."\r\n" .      'x-mailer: php/' . phpversion();      @mail($email_to, $email_subject, $email_message, $headers);        ?>       thank contacting us. in touch soon.      <?php     }      ?>