The biggest problem is that the 4/5xy codes are what to do about THAT message.
Big senders and big receivers are trying to use them to answer a different question: what to do about the NEXT message. With a few exceptions legitimate ESPs accept a 5xy as “don’t try this message again” and a 4xy as “keep trying until timeout”. (There are a couple that reattempt 5xy from different IPs, for reasons.) We have a de facto standard that’s evolved based on what the ISPs are returning and how bulk senders are interpreting them. But the SMTP response codes are not meant to transmit the information we’re using them to transmit. laura > On Jun 20, 2016, at 6:08 AM, Vick Khera <[email protected]> wrote: > > > On Mon, Jun 20, 2016 at 5:31 AM, Stefan Haunß <[email protected] > <mailto:[email protected]>> wrote: > however, IIRC there was also a M3AAWG BCP covering this questions. > > I don't recall there being a BCP about this. There was a panel discussion > last week at the conference, and most people in attendance agreed that there > needs to be much more discussion about it. The context was more in the area > of delivery rates, but I think it applies in general. > _______________________________________________ > mailop mailing list > [email protected] > https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop -- Having an Email Crisis? 800 823-9674 Laura Atkins Word to the Wise [email protected] (650) 437-0741 Email Delivery Blog: http://wordtothewise.com/blog
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