Re: [Emailcore] Proposed ESMTP keyword RCPTLIMIT

John Levine <johnl@taugh.com> Fri, 12 March 2021 20:32 UTC

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From: John Levine <johnl@taugh.com>
To: emailcore@ietf.org
Cc: laura@wordtothewise.com
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Subject: Re: [Emailcore] Proposed ESMTP keyword RCPTLIMIT
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It appears that Laura Atkins  <laura@wordtothewise.com> said:
>> max line length\
>> max number of lines
>> max number of characters for total message
>> MIME limits (eg., nesting depth)
>> Unicode or other character limits

I don't think it is a good idea to provide standard ways to say that an
implementation doesn't comply with a standard.  There's a line length limit
in the spec, it's not hard to support.

>Is there a place for ‘max connections’ - a number of places already limit the number of maximum connections that
>any sending system can make at one time. A way to mechanically advertise that might be useful. 

Intereesting question but then I ask max connections from what, a single IP, a /24,
something else?  I also worry this could be close to saying here's how to DDoS me.

Also for this particular case I'd say the excess connection should greet
with 421 and enhanced status code (it's be 4.3.7) to say too many connections.

R's,
John