DMARC, google.com and "via openbmc"

Joel Stanley joel at jms.id.au
Wed Feb 1 10:15:19 AEDT 2017


Hey OpenBMCers,

tl;dr: emails from google.com will now say "Googler Name via openbmc"
on the list. This is intentional.

The details:

DMARC is annoying for mailing lists. Instead of repeating why, you can
read about it here[1].

google.com has a "reject" DMARC policy enabled[2]. This means that
when a DMARC enforcing recipient (such as jms.id.au, hosted with
Google Apps) gets an email from a google.com address via the mailing,
the recipient mail server will reject the emails. It appears Google
Apps chooses to silently reject.

So since google.com turned this on some time late last year, I have
not been receiving any email from google.com addresses.

Our mailing list software (mailman) has an option called
dmarc_moderation_action that when enabled will perform some extra
processing on emails sent from a DMARC enabled domain. That processing
means it re-writes the From header to be "User Name via openbmc
<openbmc at lists.ozlabs.org>. This ensures the mail passes DMARC.

The Reply-To header is set as it was previously so clicking
Reply-to-All will still do the correct thing.

I've been seeing mail from Xo and Rick today which indicates things are working.

Cheers,

Joel

[1] https://wiki.list.org/DEV/DMARC
[2] https://dmarcian.com/dmarc-inspector/google.com


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