Re: [dmarc-ietf] Ticket #28 - Failure report mail loops

[Alessandro Vesely <[e-mail]>]

On Mon 07/Dec/2020 20:51:12 +0100 John Levine wrote:
> In article <[e-mail]>,
> Alessandro Vesely  <[e-mail]> wrote:
>>> 4.  Some explicit loop prevention specification may be added.  For example:
>>>> 4.1.  send reports from a subdomain having a DMARC record without ruf=, or
>>>> 4.2.  never send failure reports about failed reports.
>>> 
>>> The latter, which is consistent with SMTP never generating a bounce about a
>>> bounce.
>>
>>However, SMTP has an operational definition of bounce, MAIL FROM:<>.  Should we 
>>take the same stance?  That is, send failure reports with an empty bounce 
>>address and never send failure reports to bounces or failure reports?
> 
> We're talking about DMARC failures, not SMTP delivery failures. I
> don't see what the latter has to do with the former.


When dmarc authentication method fails on a message, an MTA may decide to send 
a failure report.  If the message is itself a failure report, however, no 
failure report should be sent.  The question is, how does the MTA determine 
whether the message is a failure report, without resorting to lengthy content 
analysis?

One possibility is to never send failure reports when the bounce address is 
empty, and mandate that failure reports be sent with an empty bounce address. 
That way, also regular SMTP bounces won't be reported if dmarc authentication 
fails.

Overly simplistic?

Ale
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