At Wed, 28 Apr 2010 16:14:59 -0400,

Matt Lundin <mdl@imapmail.org> wrote:
> David Frascone <dave@frascone.com> writes:
> > 2) Which mail subsystem would be most compatible and easiest to use? 
> > MH?  Gnus?  And, would it be worth the trouble setting up on a mac?
>
> You might want to check out this recent ML discussion:
>
> http://thread.gmane.org/gmane.emacs.orgmode/23481/focus=23588

I started that thread, the answer I suspect is simply no. Your options
are MH-E, Gnus, Wanderlust, VM and MEW. I tried Gnus, Wanderlust and
VM trying the hardest with Gnus and Wanderlust.

Gnus has a lot going for it as it is included in emacs, very active
development and I had it reading my IMAP mail very quickly. It is
however a news reader and that didn't suit me at all.

Installing Wanderlust I understand is tricky, you need to get it and
it's dependancies from the right branch from CVS as the last release
occured some time ago. I use the ubuntu wl-beta package so didn't have
to do this.

Configuration is far from trvial, my config file has 300 lines. It
took me a week of tweaking to get to a state where I was happier than
I was with my previous mail client. There are still some rough edges.

I do like and use the org integration, but have found the bigger
advantage is that I've now one less reason to leave emacs. How emacs
centric is your current computer use?

Postbox http://forums.appleinsider.com/showthread.php?t=94402 looks
like a very capable application. By all means try all 5 out, I suspect
though that they're not the mail clients you're looking for.