Rick van Rein:
> Hello,
>
> I see a lot of spam entering that claims to have come from a local
> domain, usually guessing a non-existent account. I've been looking for
> a way to "reject_unverified_local_sender", by which I mean that the
> sender address is verified iff it occurs in virtual_alias_domains (and
> perhaps a few other lists).
>
> One way to go could be to create a database of sender domains to
> validate, enter my own domains in it, and use "external" access to my
> own MTA and probing it. But that leads to cyclic probing! I suppose I
> am really looking for something simpler -- namely an invocation of the
> virtual(8) server for addresses on the said lists.
>
> I don't see how I can do this with Postfix, and it's not even simple in
> a policy due to the cyclic risk. What are others doing in this respect?
/etc/postfix/main.cf
smtpd_reject_unlisted_sender = yes
That will reject MAIL FROM commands with a non-existent local sender.
Wietse
