Moses,
Mailing lists are not loved for their UI, I doubt there is much innovation left there. UI and UX is left for apps, websites and forums where developers work every day to get things looking more swanky and ease of use going up.
We at Techweez sometime back
started a forum that nears the function of a mailing list in that outside of you getting informed of new topics and replies by visiting the forum, you can also choose notification frequency, follow specific topics (and get notified only when there is contribution in those topics), reply via email and start topics via email (we are yet to enable these two). Work in progress is a very light app that will enable one follow all these via push notifications, so you will be alerted that there is posts you need to follow and go to the browser to respond.
Beauty of this is you have all these options, choose your pick, we also have desktop notifications, so you just leave one tab open and conversation never leaves you.
Regards,
Martin Gicheru
Editor at Techweez