Re: DMARC

[Reco <recoverym4n@enotuniq.net>]

	Hi.

On Sat, Jul 10, 2021 at 12:20:24AM -0400, Polyna-Maude Racicot-Summerside wrote:
> I receive the following regarding messages sent on the mailing list...

A usual dmarc report, and you receive that because your domain has DMARC
policy set that way - it's a TXT record _dmarc.polynamaude.com.

BTW - why have you set "p=none" there?


> Someone understand something ?

Sure. Every time you send the e-mail to the list, multiple MTAs resent
your e-mail to whom they deem appropriate.
The idea of DMARC is to show you, the domain owner, how the world
perceives e-mails sent on your behalf (or not, considering the spammers).

This particular dmarc report comes from the FastMail, and it shows,
along with the other things:

1) That your e-mails go through bendel.debian.org, the MTA behind this
very list (and other Debian lists). There are others MTA there, but
bendel.d.o is the most important.

2) The fact that your DKIM policy is unnecessary strict, because your
mails to this list routinely fail to verify DKIM.

3) The fact that your SPF policy is failing, probably because your SPF
does not designate bendel.d.o as a permitted sender on your behalf.

Also, consider installing dmarc-cat package, it really useful in
interpreting those DMARC reports, as it shows DMARC report as a
human-readable text, not XML.

Reco