On 6 Aug 2018, at 14:12, Luc Pardon wrote:
On 26-07-18 17:19, Matus UHLAR - fantomas wrote:
Anyway, whole point of this discussion that working around problems
by
violating RFC and re-sending hardly (5xx) refused mail through an ISP
is
not
way to go.
No, the "whole point" of the discussion is *not* that I want to work
around just any 5xx problem.
The only "problem" that I am trying to solve is how to detect that the
other side is telling me to re-send through my ISP, so that I can
oblige.
That is NEVER the message of ANY 5xx reply. ANY 5xx reply ALWAYS
indicates that you should not resend automatically. Really. Read RFC5321
and its ancestors.
You should expect that at some point your workaround will be detected,
deemed abusive, and actively countered so that you cannot deliver your
mail by any means to some places. That may be done silently, since it is
entirely fitting that violation of basic interop rules be met with the
same.
