Dave Crocker <dcrocker(_at_)brandenburg(_dot_)com> wrote:
AD> - MTA's are MTA's for one domain
not really. ISPs that support customer-specific domain names have MTAs
that service many domains.
Now. As I said, back when RFC 821 was written, that kind of
deployment was not widely used, so the RFC's weren't written with that
configuration in mind. So now that we have that kind of
configuration, it's unclear how those MTA's should be set up.
What does it mean when an MTA delivers mail for many domains? What
is the relationship between the fields in SMTP and those domains? Is
it expected to get EHLO example.com, and MAIL FROM user(_at_)example(_dot_)net?
The current implementation and deployment of MTAs may "just work",
but that doesn't mean they're optimal, or even correct.
Alan DeKok.