<form ...>
    <!-- Your contact form goes here -->
    <input type="hidden" id="strReferrer" name="strReferrer" value="whatever" />
</form>

<input type="hidden" id="referer" name="referer" value="<?php echo $_SERVER['HTTP_REFERER']; ?>" />

<a href="/contact/contact-form.php" title="send an eMail" onclick="return(contact())">Contact the author</a>

<script>
var strReferrer = location.href;
function contact() {
window.open("/contact/contact-form.php?sourceURL="+strReferrer);
return false;}
</script>

//get the URL from the originating page (where this form has been called from)
$params  = $_SERVER['QUERY_STRING'];
...
...
// Insert '$params' into the text as part of the text to be eMailed.
// the eMail Content Header for the recepient
$_POST["text"] = $_POST["send"]["author"]." with e-mail address: ".$_POST["send"]["mail"]." sent the msg below: n <$params> n n $texto";