Recommended Tests

<?php
  if($_SERVER['REQUEST_METHOD'] == "POST") {
  
  $receiverMail = "Your email address here";
  
  $name = ltrim(rtrim(strip_tags(stripslashes($_POST['name']))));
  $email = ltrim(rtrim(strip_tags(stripslashes($_POST['email']))));
  $subject                      = ltrim(rtrim(strip_tags(stripslashes($_POST['subject']))));
  $msg = ltrim(rtrim(strip_tags($_POST['msg'])));
  
  $ip = getenv("REMOTE_ADDR");
  $msgformat = "From: $name ($ip)\nEmail: $email\n\n$msg";
  
  // VALIDATION
  if(empty($name) || empty($email) || empty($subject) || empty($msg)) {
  echo '<font color="#ff0000"><b>Unable to send email: missing fields</b></font><br /><small>(press your browser back button)</small>'; // add here a message or image for missing fields
  }
  elseif(!ereg("^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$", $email)) {
  echo '<font color="#ff0000"><b>Unable to send email: invalid email address</b></font><br /><small>(press your browser back button)</small>'; // add here a message or image for invalid email
  }
  else {
  mail($receiverMail, $subject, $msgformat, "From: $name <$email>");
  echo '<font color="#008000"><b>Email sent successfully</b></font>'; // add here a message email is successful
  }
  }
  ?></center>
  <form action="?email=send" method="post">
  <table border="0" align="left" cellpadding="6" cellspacing="0" width="450px">
  <tr>
  <td valign="middle"><b>Name:</b></td><td><input type="text" name="name" size="40" title="First and last name, last is optional"></td><tr>
  <td valign="middle"><b>Email:</b></td><td><input type="text" name="email" size="40" title="yourname@somewhere.com"></td><tr>
  <td valign="middle"><b>Subject:</b></td><td><input type="text" name="subject" size="40"></td><tr>
  <td valign="middle"><b>Comment:</b></td><td><textarea rows="7" cols="31" name="msg"></textarea></td><tr>
  <td valign="middle"><br></td><td align="left"><input type="submit" value="Send!">&nbsp;&nbsp;&nbsp;<input type="reset" value="Reset"></td>
  </tr>
  </table>
  </form>