title: Form variables failing to print when using echo $variablename
body: <p>I'm creating a form that reads in the users name and email, then emails them a voucher via a PHP file, which looks like this:</p>
  
  <pre><code>&lt;?php
  
    $deal = "offer or discount details";
  
    $to = "$email";
    $subject = "Tonights wheree voucher - $deal";
    $message = '
    &lt;html&gt;
      &lt;body&gt;
          Test email sent to &lt;?php echo $email; ?&gt;.
      &lt;/body&gt;
    &lt;/html&gt;
    ';
  
    $headers = "From: wheree &lt;no-reply@wheree.co.uk&gt;" . "\r\n" .
               "Content-type: text/html" . "\r\n";
  
    mail($to, $subject, $message, $headers);
  
  ?&gt;
  </code></pre>
  
  <p>The form:</p>
  
  <pre><code>&lt;form class="cmxform" id="details-form" method="get" action="test.php"&gt;
                   &lt;fieldset&gt;
                         &lt;p&gt;
                           &lt;input id="name" name="name" title="Please enter your full name. " size="18" class="tagcheck" minlength="5" maxlength="60" value="Name" onfocus="if(this.value==this.defaultValue){this.value=''};" onblur="if(this.value==''){this.value=this.defaultValue};" /&gt;
                         &lt;/p&gt;
                         &lt;p&gt;
                           &lt;input id="email" name="email" size="18" title="Please enter a valid email address. " class="required email" value="Email" onfocus="if(this.value==this.defaultValue){this.value=''};" onblur="if(this.value==''){this.value=this.defaultValue};" /&gt;
                         &lt;/p&gt;
                         &lt;p class="tickbox-wrapper"&gt;
                         &lt;input id="accept-tick" type="checkbox" name="vehicle" class="required" title="You must accept our Terms &amp; Conditions. " /&gt; I accept the voucher usage &lt;a href="/voucher-terms-and-conditions" alt="terms" class="terms-link"&gt;Terms &amp; Conditions&lt;/a&gt;.
                         &lt;/p&gt;
  
                         &lt;div id="RegisterErrors" style="display:none"&gt;&lt;/div&gt;
  
                         &lt;p&gt;
                           &lt;input class="submit" type="submit" value="Continue"/&gt;
                         &lt;/p&gt;
                   &lt;/fieldset&gt;
  &lt;/form&gt;
  </code></pre>
  
  <p>This works fine, but doesn't echo the variable <code>$email</code> in the received email? I've also tried using <code>$_GET["email"]</code>, but again to no success.</p>
  
  <p>Thanks in advance for your help.</p>