[chrishajer]

I think if you can take an RSS to email service, that is about the closest you would come. I don’t know of a plugin that allows replies by email. But things like Feedburner, Feedblitz and AWeber offer email to RSS for the delivery, but replies are not going to work like mailman.

If you need mailman style functions, why not use mailman? Is there something that bbPress offers that mailman does not?