[RFCI-Discuss] DSN listing of secureserver.net

[Alan Brown]

On Sun, 29 Oct 2006, Alex van den Bogaerdt wrote:

> I think IP addresses are noted because names are unreliable, not
> because people like redundant data.


FWIW: I'm responsible for Sendmail noting that forward/reverse DNS don't
match. It took quite a few rounds of mail before Eric A understood why
it was important that it get stamped - but he still resisted making it
an easy option to reject no rDNS or mismatched fcDNS.


Going back even further:

Sendmail v8 SMI used to only record a host's HELO, not the IP and Sun's
distributed sendmail kits kept doing this right up until 1999.

Sendmail V4 also only noted a HELO.

Which made them both perfect for spammers.

Thankfully there are almost no such hosts left on the public Internet
and the lessons learnt from HELO and rDNS forgeries in the past have
resulted in the better header stamping we now have.