<div id="contactform">
                                  <form id="contact" action="#">
                                    <fieldset>
                                    <span class="error" id="name_error">Please enter name !</span>
                                    <span class="error" id="email_error">Please enter email address !</span>
                                    <span class="error" id="email_error2">Please enter valid email address !</span>
                                    <span class="error" id="msg_error">Please enter message !</span>
                                    <input type="text" name="contactFormName" id="contactFormName" size="50" value="Name" class="text-input" onblur="if (this.value == ''){this.value = 'Name'; }" onfocus="if (this.value == 'Name') {this.value = ''; }" />
                                    <input type="text" name="contactFormEmail" id="contactFormEmail" size="50" value="Email" class="text-input" onblur="if (this.value == ''){this.value = 'Email'; }" onfocus="if (this.value == 'Email') {this.value = ''; }" />
                                    <input type="text" name="contactFormSubject" id="contactFormSubject"  value="Subject" class="text-input" onblur="if (this.value == ''){this.value = 'Subject'; }" onfocus="if (this.value == 'Subject') {this.value = ''; }" />
                                    <textarea cols="60" rows="10" name="contactFormMessage" id="contactFormMessage" class="text-input">Message</textarea>
                                    <br />
                                    <input type="submit" name="submitButton" class="submitButton" id="submitButton" value="Send Message"/><br class="clear" />
                                    </fieldset>
                                  </form>
                            </div><!-- end contactform -->
.....
<!-- Form Contact Script -->
<script type="text/javascript" src="js/contact.js"></script>

<?php
    $emailTo = 'email@myemail.com';
    if($contactFormSubject!=""){
    $contactFormSubject =$_REQUEST['contactFormSubject'];
    }else{
    $contactFormSubject = 'Progend Contact Form';
    }
    $contactFormName=$_REQUEST['contactFormName'];
    $contactFormEmail=$_REQUEST['contactFormEmail'];
    $contactFormMessage=$_REQUEST['contactFormMessage'];

    $body = "Name: $contactFormName nnEmail: $contactFormEmail nnMessage: $contactFormMessage";
    $headers = 'From: '.$contactFormName.' <'.$contactFormEmail.'>' . "rn" . 'Reply-To: ' . $contactFormEmail;

    mail($emailTo, $contactFormSubject, $body, $headers);
?>

jQuery(function() {
  jQuery('.error').hide();
  var messagetext = jQuery("textarea#msg");
  messagetext.focusout(function(){
        if (messagetext.val() == ''){messagetext.text('Message'); }
  });
  messagetext.focus(function(){
        if (messagetext.val() == 'Message') {messagetext.text(''); }
  });
  jQuery(".button").click(function() {
        // validate and process form
        // first hide any error messages
    jQuery('.error').hide();
      var name = jQuery("input#name").val();
        if (name=="Name" || name == "") {
      jQuery("span#name_error").show();
      jQuery("input#name").focus();
      return false;
    }
      var email = jQuery("input#email").val();
      if (email == "Email" || email == "") {
      jQuery("span#email_error").show();
      jQuery("input#email").focus();
      return false;
    }

    var emailReg = /^([w-.]+@([w-]+.)+[w-]{2,4})?$/;
    if(!emailReg.test(email)) {
    jQuery("span#email_error2").show();
    jQuery("input#email").focus();
      return false;
    }

      var subject = jQuery("input#subject").val();
      if (subject == "") {
      jQuery("input#subject").focus();
      return false;
    }
      var msg = jQuery("textarea#msg").val();
      if (msg == "Message" || msg == "") {
      jQuery("span#msg_error").show();
      jQuery("textarea#msg").focus();
      return false;
    }

        var dataString = 'name='+ name + '&email=' + email + '&subject=' + subject + '&msg=' + msg;
        //alert (dataString);return false;

      jQuery.ajax({
      type: "POST",
      url: "process.php",
      data: dataString,
      success: function() {
        jQuery('#contactform').html("<div id='message'></div>");
        jQuery('#message').html("<b>Contact Form Submitted!</b>")
        .append("<p>We will be in touch soon.</p>")
        .hide()
        .fadeIn(1500, function() {
          jQuery('#message');
        });
      }
     });
    return false;
    });
});

$(".submitButton").click(function(){ [...]});

success: function(response) {
    jQuery('#contactform').html("<div id='message'>"+response+"</div>");

if(mail($emailTo, $contactFormSubject, $body, $headers))
 echo "success!";