Re: [Emailcore] Proposed ESMTP keyword RCPTLIMIT

[Laura Atkins <[e-mail]>]

> On 12 Mar 2021, at 20:32, John Levine <[e-mail]> wrote:
> 
> It appears that Laura Atkins  <[e-mail]> 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?  

That would be for the folks advertising to say what they’re using and what they’re limiting by. The limits are actively in place, it’s just do we want to describe them in a more formal way. 

> I also worry this could be close to saying here's how to DDoS me.

The limits I was thinking of are policy not technology. Alex brings up a good point that the limits are not set in stone but do change depending on the reputation of the sender / mailstream / IP address. 

> 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.

Makes sense. 

laura 

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