I was sort of thinking that perhaps the FAQ should contain something
about how to do it right if you think you really have to use Procmail
for this. The solution I have in mind is to collect all recipients in
a variable and then forward to all those people in one fell swoop, but
I'm not sure this is the best solution in all circumstances. (If you
want to, say, save to their spool files rather than forward [which
sounds like a stupid idea, but I might be overlooking something ...
anyway, why would you not deliver to those users in the first place if
you know how to do that reliably?] you will need to loop if the spools
are normal mbox format ones.)
I posted a "solution" back in April of '98 that might be useful.
It's in the archives as
http://www.xray.mpe.mpg.de/mailing-lists/procmail/1998-04/msg00289.html
with a Message-id: of
<199804291457(_dot_)JAA18580(_at_)ferret(_dot_)ncsa(_dot_)uiuc(_dot_)edu>
Not only does it redirect the mail (based on ^TO), but the sendmail.cf
mods should fix the relevant headers.
Chris