[Mimedefang] Revisit: Filtering on HELO

[Cormack, Ken]

> A lot of hosts say "HELO 1.2.3.4" when their address
> is really 5.6.7.8.

> If they can't be trusted to figure out their own
> address, then they're probably pretty broken (and
> that includes being behind a NATing firewall as we
> are).

Our they are COMPLETELY capable of figuring out their true IP address... But
then are NAT'd behind a firewall... Or...

::ducking::