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Re: [ietf-smtp] SMTP Greylisting Retry Hints + PRDR

2019-02-08 09:41:10
Jeremy Harris <jgh(_at_)wizmail(_dot_)org> wrote:
On 08/02/2019 15:21, John R Levine wrote:

How reliably does that work?  If I were writing an MTA I'd think a mix
of 2xx and 5xx is likely but 2xx and 4xx is unexpected.

Works fine with Exim; I'd call your MTA nonconforming if
if it didn't handle it.


There are situations where this can happen that are nothing to do with
disgusting filtering hacks :-) e.g. if the server is validating recipient
addresses and some of them depend on DNS lookups which fail.

f.anthony.n.finch  <dot(_at_)dotat(_dot_)at>
Forties, Cromarty, Forth: South, veering west later, 6 to gale 8, perhaps
severe gale 9 later. Rough or very rough. Rain or showers. Good occasionally
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