What if neither to-list nor to-address is right?

[Kai Grossjohann <grossjohann@charly.cs.uni-dortmund.de>]

Hi,

I've got a group which corresponds pretty much but not exactly to a
mailing list.  to-list is not a good parameter because people tell me
they get duplicate mail when I just hit "F".  to-address is not a good
parameter because that sets the To address always to the mailing list
address, but there are some people not on the list that I might want
to send mail to (by hitting "F").

Is there a way to tell Gnus the following?

    I want to-list for this group, but don't send mail to jrl@foo.com
    if you already send it to mailing@list.org because jrl@foo.com is
    a member of that mailing list.

tia,
kai
-- 
A large number of young women don't trust men with beards.
(BFBS Radio)