Re: [Exim] Detecting open relays in Received path

From: <michael@???>
> I second that: Don't block mails from hosts listed in ORBS. Many people
> will yell at you otherwise.

I'm not in the habit of yelling at myself (except when I bang my toe or drop
my car keys down a grate). Doh, I knew this discussion would turn meta almost
immediately but hate pre-emptively disclaiming against it 'cos it sounds
rude.

So, if anyone has any suggestions on actual solutions for detecting messages
that have passed through an open relay upstream I would be interested to hear
if only for the fun of having solved that particular problem. I've
investigated pulling out IP addresses from Received: and then using perl's
Net::DNS::Resolver to check them but it feels ultra-heavyweight and isn't
desperately quick. I think a maps lookup type that, based on contents of
rbl_domains, returns nothing, reject or warn (i.e. the bit after the /) would
be a great start and perhaps be generically interesting for other
applications. How hard would that be to implement? Perhaps there's a better
way?

Paul