Re: [ietf-smtp] DSNs

Arnt Gulbrandsen <> Sun, 26 April 2020 10:31 UTC

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From: Arnt Gulbrandsen <>
Date: Sun, 26 Apr 2020 12:31:04 +0200
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Subject: Re: [ietf-smtp] DSNs
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On Saturday 25 April 2020 23:15:23 CEST, Ned Freed wrote:
> Completely inapplicable in this case, I'm afraid. One of the 
> primary goals of
> the NOTARY effort, if not the primary goal, was feature parity with X.400.
> And the operational model for X.400 was success receipts as the default.
> So the feature had to be part of the core. 
> But thinkgs change. X.400 collapsed - a casualty of even more serious
> design errors than success DSNs. Spam became email's biggest problem,
> which made NOTIFY=SUCCESS less desirable. Privacy concerns also arose that
> weren't even on the radar at the time this work was done.

X.400 collapsed, other things appeared. Delivery and display receipts 
appear to be popular features of some human-to-human instant messaging 
systems nowadays — I've heard that Signal added that precisely because it 
was popular with Telegram users. That's a rumour, but that both have 
delivery receipts is a fact.

I've no idea what the problems with notify=success are considered to be, so 
I don't know whether Signal/Telegram/Threema/… have equivalent problems, or 
whehter the problems relate to some aspect of the implementation that is 
not shared by those IM implementations. I'd love to know.