I am trying to get set up with S/MIME.  I have no personal cert yet, but
I have imported a correspondent's key and CA cert and marked the CA
trusted.  gpgsm on the command line will verify a message.

I read this:

  http://www.emacswiki.org/emacs/GnusSMIME

and set: (setq mml-smime-use 'epg)

which seems to be the default these days if epg exists.

(I am using gnus from git master, via load-path, and emacs 23.4.1.)

But I still get "No CA configured" when displaying a message (which is
really a base-64 encoded s/mime signed message).

This is in smime-verify-region which is the openssl variant.

Can someone tell me what the best thing to do is for S/MIME?  (I have
been happily using OpenPGP with epg for many years.)