Milter-greylist

> By the way, thanks to everybody else for explaining that
> the problem cannot easily be solved.  So far the best
> suggestion was given by Emmanuel, i.e. to use the milter-
> rcpfilter.  However, the problem is that it has is own
> configuration file of valid users, so I would have to
> maintain users in multiple different places, which is
> annoying and error-prone.

I've solved the problem by listing all valid email addresses
that should be protected by greylisting in greylist.conf,
and changing the default action to whitelist, like:

  acl greylist rcpt user1@...
  acl greylist rcpt user2@...
  acl whitelist default

Like this you don't need an extra milter. You still have to
maintain the list of valid e-mail addresses in greylist.conf.
If accounts aren't added/deleted frequently, that's not a big
issue. But even if so, you could generate the greylist.conf
entries (semi-)automatically with a script. It's not a problem
if a new account isn't listed immediately, as the default is
whitelist, and new accounts take some time to catch big amounts
of spam anyway.

mp.
-- 
                         Martin Paul | Systems Administrator
   Institute of Scientific Computing | martin@...
 Nordbergstrasse 15/C/3, A-1090 Wien | Tel: 01 4277 39403
        http://www.par.univie.ac.at/ | Fax: 01 4277 9394