GPG handling is sometimes (frequently) odd :(

So, sometimes I get gpg encrypted mail and things 'just work' (M-x
epa-mail-decrypt). Then there are, I think mostly mac-mail, gpg encrypted messages which are presented to me as:

"
This part is encrypted.
[1 PGP/MIME Versions Identification <application/pgp-encrypted (7bit)>]
"

which... I can only decrypt by saving the whole item to disk (E) and
then manually gpg decrypting.

I think this is some mismanagement of MIME parts by WL, but I'm not
clear where that's happening :( The headers for the latest message like this are:

--------- snip -------------
...
Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\))
Content-Type: multipart/encrypted; boundary="Apple-Mail=_AEC4C802-6D88-42B5-B9C3-62E29BDEB057";
 protocol="application/pgp-encrypted";
X-Pgp-Agent: GPGMail
...
Content-Description: OpenPGP encrypted message

This part is encrypted.
[1 PGP/MIME Versions Identification <application/pgp-encrypted (7bit)>]

----------end snip----------

For folk that use gpg + wanderlust, have you NOT seen this sort of
problem? or is it a common failure that has a solution I've not bing'd
correctly? or maybe epa-mail-<somethingelse> should be used here?

-chris