One can think about implementing "Mailman integration" or something, but I find that rather overdoing it. Mailman is simple enough that you can add a clean subscription form to your ikiwiki site in seconds, just add:

<form action="https://listes.example.com/cgi-bin/mailman/subscribe/listname" method="POST">
Email: <input name="email" />
<input type="submit" value="Subscribe" />
</form>

To your site and voilà, you are done! No more scary mailman subscription form! (Thanks to bgm for that trick!) --anarcat