> On Dec 19, 2019, at 7:00 PM, Bob Proulx <b...@proulx.com> wrote:
>
> "By default, the Postfix SMTP client moves on the next mail
> exchanger. Specify "smtp_skip_5xx_greeting = no" if Postfix should
> bounce the mail immediately. Caution: the latter behavior appears to
> contradict RFC 2821."
>
> But regardless that is exactly the answer I needed! I am going to set
> that for my friend's system as I think that is the best setting.
Actually, it may not be. You may end up losing mail when you
encounter overloaded servers returning 554.
In a bit of synchronicity, just a day or two ago I was corresponding
on this very question with Wietse, because there's an effort underway
to polish RFC5321 with a goal of making SMTP a "full" Internet Standard
(it only takes ~40 years). As part of that, I'd like to see a couple
of the murkier bits clarified:
* The 552 -> 452 work-around, that should no longer (if ever)
be necessary:
https://mailarchive.ietf.org/arch/msg/ietf-smtp/fhKAX0Z9frJxUxmZylthJ_LijMM
* The semantics of 554 greetings:
https://mailarchive.ietf.org/arch/msg/ietf-smtp/NeHzVodzZX6kJFJ7lQhuP6gOpWA
--
Viktor.
