From: J C Lawrence <claw(_at_)kanga(_dot_)nu>
...
Thanks, this is preferable to RMX.
It seems it also differs from Paul's intent. However, I think the
differences are minor. Both involve overloading MX RRs and depend
on using keys or values that are unlikely to be in current use.
I'm not sure, but I think Paul's intent (or Jim Miller's idea) does
better on that score.
To determine if an STMP client is authorized to send mail for the
sender domain name in the envelope Mail_From field
I'd be happier if a straight forward check of the HELO==IP were added as
a check.
I think that's independent of the idea of RMX checking.
The problem with checking HELO values is that simple implementations
will have many false positives. It's a hassle to make an SMTP client
vary its HELO value depending on the IP address that operating system
picks on a multi-homed system. Forcing the choice of source IP address
is impractical on multi-homed systems acting as firewalls and where
some interfaces are not reachable from various networks. You would
at least want to let a big outfit use a HELO value of domain.com on
all of its SMTP servers.
Vernon Schryver vjs(_at_)rhyolite(_dot_)com
_______________________________________________
Asrg mailing list
Asrg(_at_)ietf(_dot_)org
https://www1.ietf.org/mailman/listinfo/asrg