Re: [ietf-smtp] Possible cont4ibution to moving forward with RFC5321bis SMTP

[Hector Santos <[e-mail]>]

On 1/2/2020 12:18 PM, Keith Moore wrote:
> On 1/2/20 10:47 AM, Hector Santos wrote:
>
>>
>> With hosted end-users, the false positives seen with NATs has been
>> addressed with the SUBMIT protocol or some other client
>> authentication that raised the SMTP bar and allowed for receiver
>> restrictions.

> In these days of complete IPv4 address space exhaustion, it can not be
> safely assumed that there is no NAT between the MSA and the MX SMTP
> server.

Correct.

My approach is how to deal with the exceptions to a well-defined SMTP 
protocol element.   The good intention exceptions will normally 
address the issue promptly, reports are made, including server 
whitelisting, client authentication, etc. The bad intention exceptions 
don't give a hoot.

So by applying frontend SMTP compliancy-based osmosis filters first, 
you will expect to see fast detection and correction of the good 
stream, leaving behind the bad stream and less complaints.  That is 
exactly what has happen, what I have experienced, my customers have 
experienced, in the 17 years of applying these SMTP compliancy filters.

Thanks

-- 
HLS