Trouble fetching encrypted messages w/nnimap

[Bjorn Solberg <bjorn_ding@hekneby.org>]

My setup:

GNU Emacs 21.3.1 (i386-mingw-nt5.1.2600) of 2004-03-10 on NYAUMO
No Gnus v0.3 (from gnus-CURRENT-20050304.tar.gz)

I'm talking to the IMAP server (which is a Lotus Notes server) as
a secondary method:
(setq gnus-secondary-select-methods
      '((nnimap "notes1")))

Some messages I receive are encrypted, and I see

---- 8< ----
[Portions of this MIME document are encrypted with a Notes certificate and
cannot be read.]
---- 8< ----

in the Article buffer instead of the actual message.  The Notes client of
course have no trouble reading it.  Can I teach Gnus how to decrypt those
messages?  I'm sure some certificate file is around somewhere, provided
Notes is actually using something standardized for the encryption.  

Given that the encrypted data doesn't seem to make it over (*imap-debug*
doesn't show the body of the IMAP stream), does that mean that nnimap
then somehow have to communicate this to the Notes IMAP server?  I don't
know what kind of encryption Notes uses nor do I know how the encryption
works across IMAP.  Is this a known issue?  If so, any pointers to a
solution would be much appreciated.

Thank you,

Bjorn.