<?php
function hide_mailto($mail, $label, $subject = "", $body = "") {
    $chars = preg_split("//", $mail, -1, PREG_SPLIT_NO_EMPTY);
    $new_mail = "<a href=\"mailto:";
    foreach ($chars as $val) {
        $new_mail .= "&#".ord($val).";";
    }
    $new_mail .= ($subject != "" && $body != "") ? 
"?subject=".$subject."&body=".$body : ""; // Let op het '&' teken is nu gewijzigd in &amp;
    $new_mail .= "\">".$label."</a>";
    return $new_mail;
}
// voorbeeld: 
echo hide_mailto("you@mail.nl", "Mail link", "Een mail van de website", "Hallo, ")
?> 