Serge Fonville:
> >> I *think* the short, correct answer is to use a policy server:
> >> http://www.postfix.org/SMTPD_POLICY_README.html
> > I will look into those then
> I read into http://www.postfix.org/SMTPD_POLICY_README.html, but I do
> not see how I can use this to solve my problem.
> Perhaps I am missing something...
>
> Any help is greatly appreciated
The policy server can reject mail from a remote network with a
local sender address.
Isn't that what you want?
As an added bonus, it can also reject mail from a local network
with a remote sender address. This can help to stop outbound spam
from zombie-infested PCs.
Wietse