Code:
<script>
<!--
// "ihrname" = prefix der email (username)
// "ihredomain.de" der rest der email-adresse.
var prefix = "meine";
var domain = "homepage.org";
document.write('<a id=\"email\" href=\"mailto:' + prefix + '@' + domain + '\">');
document.write(prefix + '@' + domain + '</a>');
//-->
</script>