I don't need to. Some 5xx codes, like 551, *are* already advisory in
rfc2821. It just means "can't deliver it that way, but try this other
way". 551 has been proposed as an alternative to SRS.
Nowhere in 2821 is 551 treated as anything but a permanent error. It
continues to be a "Permanent Negative Completion reply" in the 5yz
range. 551 is noted as more correctable -- *via a new message
envelope* -- than other permanent errors. By definition, any such
"correction" cannot occur in real-time: even if the error might not
exist minutes later, the DSN resulting from a 551 _must never
represent that the submitted message could be delivered_. Therefore,
it will always appear to the user as a permanent failure alongside
everything else they call the help desk about.
Unless the majority of MTAa specifically change the format of their
DSNs for 551s (or for some reserved enhanced status code) to hide the
"permanent" part and show a happy, clickable URL instead, the idea of
using any 5xx code for C/R is dead in the water. IMO, one would be
better off lobbying for a new 4xx code that instructs "keep retrying
with this exact message object, but *also* send a transient DSN with
the following happy text" -- which covers more bases. But I wouldn't
spend my time lobbying for either one.
Look, I don't use C/R. But I *do* do a much better job of spam
abatement with my "hobbiest" software than the big email providers.
I believe that. I have many colleagues that do boutique anti-abuse
hosting that do a better job than the big guys as well. But none of
them, including you, use C/R to do it. And you wouldn't be any more
likely to be able to get away with C/R for your customer base if you
used this phantasmic envelope-time rejection idea.
--Sandy
-------------------------------------------
Sender Policy Framework: http://www.openspf.org
Modify Your Subscription: http://www.listbox.com/member/
Archives: https://www.listbox.com/member/archive/735/=now
RSS Feed: https://www.listbox.com/member/archive/rss/735/
Powered by Listbox: http://www.listbox.com