Incoming SMTP in the year 2017 and absence of DKIM

[johnl at iecc.com (John Levine)]

In article <85393a12-a51f-6722-4171-118919fcc2d0 at mtcc.com> you write:
>The real problem with large enterprise that we found, however, is that 
>it was really hard to track down every 25 year
>old 386 sitting in dusty corners that was sending mail directly instead 
>of through corpro servers to make certain
>that everything was signed that should be signed. Maybe that's gotten 
>better in the last 15 years, but I'm not too hopeful.

No kidding.  That's why you publish a DMARC policy record that says
don't treat my mail any differently, but please send me summary
reports about it.  This lets you see where mail with your From: domain
is coming from, to track down all those dusty servers.  Once you've
found them all, then you can decide whether publishing a policy is
likely make things better or worse.

You'll also find a whole lot of Chinese botnets that send out spam
with random return addresses including yours, but they're not hard to
tell apart.

R's,
John