It's a good question. I hope so, but I guess not - at best, a good email client will have some functionality that improves things a bit. Possible workflow:
- a filter that puts all messages from one mailing list into a folder
- enable Threaded View for that folder and possibly some other things that make it less "ugly" to you.
If email itself isn't interactive enough for you, I don't see how to increase that with email. And what have PRs got to do with mailing lists per se?