On Jul 18, 2014, at 7:50 AM, Ted Lemon
<ted(_dot_)lemon(_at_)nominum(_dot_)com> wrote:
I must be missing something here. You're saying you want me to set up a
null MX for all my hosts to prevent someone else's MTA having undeliverable
mail sitting in the queue for a week? Why would I care about your MTA's
queue? Why would this issue even be on my radar?
It could be useful as an optimizer to avoid the implicit mx step. It can also
help with any CBV "call back verifiers" support to immediately skip checking
the return path dynamically at the SMTP level. This would provide your
receiver with a "55z 5.5.z invalid return path" dynamic rejection at the 5321
mail from or rcpt to state point.
So in this regard, on the receiver side, it is definitely become a valid SMTP
compliance check with an enforceable reason to reject regardless of the mail
legitimacy. On the sender side, it's an optimizer to avoid the implicit mx
attempt.
--
Hector Santos
http://www.santronics.com