Re: [dmarc-ietf] Fwd: New Version Notification for draft-crocker-dmarc-sender-01.txt

[Alessandro Vesely <[e-mail]>]

On Mon 27/Jul/2020 22:12:17 +0200 Joseph Brennan wrote:
>> On 7/27/2020 11:14 AM, Alessandro Vesely wrote:
>>
>>> Let's say I have From: real.bank, and Sender: phisher.example. The
>>> above text seems to imply the receiver is looking up
>>> _dmarc.phisher.example.  Correct?
>>
> 
> Avoiding it by redefining From: to serve the former purpose of Sender: and
> creating a new Author: to serve the former purpose of From: seems to me to
> start us down a long road of new header fields every couple of years. They
> are just names.


In the pre-DMARC era, we've been mainly using just From:.  Sender: is used by 
Outlook to display "on behalf of" catchphrase, presumably in an attempt to 
support the historic Sender-Id protocol.  Otherwise, Sender: never had 
traction.  DMARC did put an extra accent on From:, thereby projecting the 
community into a /new territory/, to use Dave's words.

Introducing Sender: and Author: can allow to tone down DMARC rules.  They were 
designed presuming that only a few domains, where email is not used for 
personal correspondence, would use the protocol.  For example, messages cannot 
have multiple authors, and cannot be forwarded with modifications.  Somewhat 
Procrustean for day to day messaging.

From: rewriting is an obnoxious hack.  Yet it's the only possibility for MLMs, 
currently.  By (re-)introducing those two header fields, we can bevel DMARC 
rules, paying attention not to pervert the overall shape.  Three identifiers 
allow better tuning than just one.  If we do a good job, it won't be necessary 
to redo it every couple of years...


Best
Ale
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