esse é  código PHP que estou usando:
 
	<?php 
	// EDIT THE 2 LINES BELOW AS REQUIRED 
	$send_email_to = "atendimento@optionmaker.com.br"; 
	$email_subject = "Contato Site Mobile"; 
	function send_email($name,$email,$email_message) 
	{ 
	  global $send_email_to; 
	  global $email_subject; 
	  $headers = "MIME-Version: 1.0" . "\r\n"; 
	  $headers .= "Content-type:text/html;charset=iso-8859-1" . "\r\n"; 
	  $headers .= "From: ".$email. "\r\n"; 
	  $message = "<strong>Email = </strong>".$email."<br>"; 
	  $message .= "<strong>Name = </strong>".$name."<br>";   
	  $message .= "<strong>Message = </strong>".$email_message."<br>"; 
	  @mail($send_email_to, $email_subject, $message,$headers); 
	  return true; 
	}
 
	function validate($name,$email,$message) 
	{ 
	  $return_array = array(); 
	  $return_array['success'] = '1'; 
	  $return_array['name_msg'] = ''; 
	  $return_array['email_msg'] = ''; 
	  $return_array['message_msg'] = ''; 
	  if($email == '') 
	  { 
	    $return_array['success'] = '0'; 
	    $return_array['email_msg'] = 'email is required'; 
	  } 
	  else 
	  { 
	    $email_exp = '/^[A-Za-z0-9._%-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,4}$/'; 
	    if(!preg_match($email_exp,$email)) { 
	      $return_array['success'] = '0'; 
	      $return_array['email_msg'] = 'enter valid email.';   
	    } 
	  } 
	  if($name == '') 
	  { 
	    $return_array['success'] = '0'; 
	    $return_array['name_msg'] = 'name is required'; 
	  } 
	  else 
	  { 
	    $string_exp = "/^[A-Za-z .'-]+$/"; 
	    if (!preg_match($string_exp, $name)) { 
	      $return_array['success'] = '0'; 
	      $return_array['name_msg'] = 'enter valid name.'; 
	    } 
	  } 
	         
	  if($message == '') 
	  { 
	    $return_array['success'] = '0'; 
	    $return_array['message_msg'] = 'message is required'; 
	  } 
	  else 
	  { 
	    if (strlen($message) < 2) { 
	      $return_array['success'] = '0'; 
	      $return_array['message_msg'] = 'enter valid message.'; 
	    } 
	  } 
	  return $return_array; 
	}
 
	$name = $_POST['name']; 
	$email = $_POST['email']; 
	$message = $_POST['message'];
 
	 
	$return_array = validate($name,$email,$message);
 
	if($return_array['success'] == '1') 
	{ 
	    send_email($name,$email,$message); 
	} 
	header('Content-type: text/json'); 
	echo json_encode($return_array); 
	die(); 
	?>
 
	 
 
	Este é o código HTML que estou usando:
 
	<form method="post" action="send_form_email.php" id="contactform"> 
	                    <div> 
	                        <label for="name">Nome</label> 
	                        <input type="text" class="input-field" id="name" name="name" value=""> 
	                    </div> 
	                    <div> 
	                        <label for="email">E-mail</label> 
	                        <input type="text" class="input-field" id="email" name="email" value=""> 
	                    </div> 
	                    <div> 
	                        <label>Mensagem</label> 
	                        <textarea id="message" name="message"></textarea> 
	                    </div> 
	                    <a id="button-send" href="#" title="Send Email" class="button" style="width:100%;">Enviar</a> 
	                    <div id="success">Mensagem enviada com sucesso!</div> 
	                    <div id="error">Ops! Algo deu errado. Use o atendimento@optionmaker.com.br</div> 
	                </form>