Re: [ietf-smtp] parsing SMTP replies (was: Proposed ESMTP keyword RCPTLIMIT}

Keith Moore <moore@network-heretics.com> Thu, 18 March 2021 02:39 UTC

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From: Keith Moore <moore@network-heretics.com>
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Date: Wed, 17 Mar 2021 22:39:48 -0400
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Subject: Re: [ietf-smtp] parsing SMTP replies (was: Proposed ESMTP keyword RCPTLIMIT}
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On 3/17/21 9:37 PM, Sam Varshavchik wrote:

>
> I believe that the generally good track record of historical 
> interoperability of SMTP implementations goes back to what's in 
> section 4.5.3 of RFC 821, that gives the minimal limits of various 
> things, like line lengths. And, incidentally, the minimum number of 
> recipients that an SMTP server should accept is 100 recipients. 

It's been a long time but I'm pretty sure I've seen situations in which 
it made sense for the recipient limit to be 1.   For example: a 
special-purpose device (e.g. email to fax, email to printer) or a 
gateway to a dissimilar mail system, or anything for which it makes 
sense to insist that per-recipient errors get immediately reported to 
the client.

Keith