On Thu, Mar 29, 2012 at 4:04 PM, David Jeske <davidj@gmail.com> wrote:

...

• Merging of forums, archives, newsgroups, and IMAP.

You like to bite off the big ones eh? NNTP, then IMAP.

Does anyone even use fat-mail-clients anymore?

Yes, and yes. But I don't think anybody has really thought carefully about these desiderata yet, they're just frequently suggested on mailman-users and sometimes mailman-developers.