I don’t think that any developer is going to pour much in the way of resources into an email client, so The Bat and Pocomail will go the way of Eudora.

So too Mulberry, alas.  I've used it for more than a decade, and I still love it, but it hasn't had any noticeable development in about five or six years, and it certainly needs some.  But every time I try a different email client, I'm reminded why I stay with Mulberry.