PHP thank you only on successful submission - php

Question

So I have a form with both javascript validation to check each field is filed and a jquery ajax script to stop the page reloading.
The PHP script is very simple and only emails the fields of the form.
The problem is I need to ONLY show the thank you message if each field is filled out, and at the moment it appears to be showing it when I just enter the name field.
It doesn't show it if i just enter either the email or message field though and I can't work out why (I'm bad at PHP).
<?php
$name = $_POST['name'];
$email = $_POST['email'];
$priority = $_POST['priority'];
$message = $_POST['message'];
$telephone = $_POST['telephone'];
$formcontent="From: $name \n Email: $email \n Telephone Number: $telephone \n Priority: $priority \n Message: $message";
$recipient = "myemail#address.co.uk";
$subject = "Contact Form";
$mailheader = "From: $email \r\n";
mail($recipient, $subject, $formcontent, $mailheader) or die("Error!");
if(mail($name,$email,$message,$headers)){
echo "<p>Thanks for your mail...</p>";
}
?>
Javascript that stops page reloading.
<script type="text/javascript">
$(document).ready(function() {
$(".contactus").submit(function() {
$.post("mail.php", $(".contactus").serialize(),
function(data) {
$("#formResponse").html(data);
}
);
return false;
});
});
</script>
Form validation.
<script type="text/javascript" language="JavaScript">
var FormName = "contactus";
var RequiredFields = "name,email,priority,message";
function ValidateRequiredFields()
{
var FieldList = RequiredFields.split(",")
var BadList = new Array();
for(var i = 0; i < FieldList.length; i++) {
var s = eval('document.' + FormName + '.' + FieldList[i] + '.value');
s = StripSpacesFromEnds(s);
if(s.length < 1) { BadList.push(FieldList[i]); }
}
if(BadList.length < 1) { return true; }
var ess = new String();
if(BadList.length > 1) { ess = 's'; }
var message = new String('\n\nThe following field' + ess + ' are required:\n');
for(var i = 0; i < BadList.length; i++) { message += '\n' + BadList[i]; }
alert(message);
return false;
}
function StripSpacesFromEnds(s)
{
while((s.indexOf(' ',0) == 0) && (s.length> 1)) {
s = s.substring(1,s.length);
}
while((s.lastIndexOf(' ') == (s.length - 1)) && (s.length> 1)) {
s = s.substring(0,(s.length - 1));
}
if((s.indexOf(' ',0) == 0) && (s.length == 1)) { s = ''; }
return s;
}
// -->
</script>
And the form
<form action="mail.php" id="myform" class="contactus" onsubmit="return ValidateRequiredFields(); this.submit(); this.reset(); return false;" name="contactus" method="POST">
<p class="floatleft" style="width:200px; background-color:#FF0000; height:50px; line-height:50px; margin:0; padding:0;">Nameeeeee</p> <input class="sizetext" type="text" maxlength="10" name="name">
<div style="clear:both"></div>
<p class="floatleft" style="width:200px;">Email</p> <input class="sizetext" type="text" maxlength="10" name="email">
<div style="clear:both"></div>
<p class="floatleft" style="width:200px;">Telephone</p> <input class="sizetext" type="text" maxlength="10" name="telephone">
<p>Priority</p>
<select name="priority" size="1">
<option value="Low">Low</option>
<option value="Normal">Normal</option>
<option value="High">High</option>
<option value="Emergency">Emergency</option>
</select>
</select>
<p>Message</p><textarea name="message" rows="6" cols="25"></textarea><br />
<br />
<input class="buttonstyle" type="submit" value="Send">
</form>

Answer 1

<?php
$name = $_POST['name'];
$email = $_POST['email'];
$priority = $_POST['priority'];
$message = $_POST['message'];
$telephone = $_POST['telephone'];
$check = array('name', 'email', 'priority', 'message', 'telephone');
$send = true;
foreach($check as $key => $value){
if(empty($_POST[$value])){
$send = false;
}
}
$formcontent="From: $name \n Email: $email \n Telephone Number: $telephone \n Priority: $priority \n Message: $message";
$recipient = "myemail#address.co.uk";
$subject = "Contact Form";
$mailheader = "From: $email \r\n";
if($send && mail($recipient, $subject, $formcontent, $mailheader)){
echo "<p>Thanks for your mail...</p>";
}
else{
die('Error!');
}

Answer 2

Well, the most easier way would be to check if your POST fields are present and not empty. Probably there is a more elegant solution if you want to check every field individually, but here goes:
if (isset($_POST['name']) && !empty($_POST['name']) && isset($_POST['email']) && !empty($_POST['email']) && isset($_POST['message']) && !empty($_POST['message'])) {
if(mail($name,$email,$message,$headers)){
echo "<p>Thanks for your mail...</p>";
}
}

Answer 3

You need to wrap your code around
if(isset($_POST['submit']))
{
$name = $_POST['name'];
$email = $_POST['email'];
$priority = $_POST['priority'];
$message = $_POST['message'];
$telephone = $_POST['telephone'];
$formcontent="From: $name \n Email: $email \n Telephone Number: $telephone \n Priority: $priority \n Message: $message";
$recipient = "myemail#address.co.uk";
$subject = "Contact Form";
$mailheader = "From: $email \r\n";
$mail = #mail($recipient, $subject, $formcontent, $mailheader);
if($mail){
echo "<p>Thanks for your mail...</p>";
}
else
{
echo "Error Sending Mail " ;
}
}