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

2019-02-05 15:03:58
Hello Hector,

I have not read your proposal, but I guess its purpose is to communicate to the 
other party (smpt-client) when to retry
transmission, in order to mitigate to minimum the delays from grey listing.  
This is great, but there is one more
application of the proposed extension, that is not called “grey listing”:

When a mail for many recipients is send and different recipients have different 
accept/reject policies, PRDR is the non-
plus-ultra.  When the SMTP parties do not agree on PRDR, the server can accept 
the email for the first recipient and all
other recipients of the mail, that have the same accept/reject policy as the 
first recipient.  All other RCPT TO:s are
told to retry later *immediately*.

This enables, to apply different accept/delay policies per email recipient 
without having PRDR and without causing
noticeble delays for any recipient.

Consider updating the “Introduction” and “Abstract” of your draft accordingly.


On Tue, 2019-02-05 at 11:11 -0500, Hector Santos wrote:
Which smtp servers and client follow or honor Greylist SMTP retry hint 
for rescheduling retries?

I wrote this draft a while ago, wondering if any software beside mine, 
Wildcat! SMTP, supports it?

It has been every efficient and it has helped minimized the retry 
attempts for delivery of mail to 2 with the shortest period.

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