[Mailman-Users] cause of bounces

[Mark Sapiro]

On 10/10/2017 07:44 PM, Paul Arenson wrote:
> So your judgment would be for Yahoo users in particular to get a new address? How about hotmail, outlook, or gmail users?

; <<>> DiG 9.10.3-P4-Ubuntu <<>> txt _dmarc.hotmail.com
...
;; ANSWER SECTION:
_dmarc.hotmail.com.	3600	IN	TXT	"v=DMARC1; p=none; sp=quarantine;
pct=100; rua=mailto:d at rua.agari.com; ruf=mailto:d at ruf.agari.com; fo=1"

; <<>> DiG 9.10.3-P4-Ubuntu <<>> txt _dmarc.gmail.com
...
;; ANSWER SECTION:
_dmarc.gmail.com.	274	IN	TXT	"v=DMARC1; p=none;
rua=mailto:mailauth-reports at google.com"

; <<>> DiG 9.10.3-P4-Ubuntu <<>> txt _dmarc.outlook.com
;; ANSWER SECTION:
_dmarc.outlook.com.	3600	IN	TXT	"v=DMARC1; p=none; pct=100;
rua=mailto:d at rua.agari.com; ruf=mailto:d at ruf.agari.com; fo=1"


I.e., all of those domains CURRENTLY publish DMARC p=none. Who knows
what they might do tomorrow. I personally don't think it's likely that
they will change for various reasons including the fact that DMARC
p=reject policies are not designed for and not appropriate for freemail
providers, but I have no crystal ball.

Yahoo began publishing DMARC p=reject (inappropriately IMO) in response
to various Yahoo security breaches. Smart people at Yahoo believe it was
worth it for the good it did them in spite of the disruption it causes
to mailing lists. AOL quickly followed - who knows what motivates AOL.


> Of course they could,  I assume, keep those addresses for nob mailing list stuff and open a new account for mailing lists with protonmail, tutanova etc if they do not have a company or school address (and forward to a mail client if they know how to do that-which many of my users being language teachers seem to be resistant to understanding-grin).
> Any recommendations on big email companies that are safe?
> And would you limit it to Yahoo or tell others on hotmail and gmail having trouble the same?


If you want to go that route, set dmarc_moderation_action (or if you're
confused by that)

Action to take when anyone posts to the list from a domain with a DMARC
Reject/Quarantine Policy.
(Details for dmarc_moderation_action)

to "Reject" and set

Text to include in any rejection notice to be sent to anyone who posts
to this list from a domain with a DMARC Reject/Quarantine Policy.
(Edit dmarc_moderation_notice)

to something like:

"You are not allowed to post to this list From: a domain that publishes
a DMARC policy of reject or quarantine. For more information see
<https://wiki.list.org/DEV/DMARC>."

or some other message.

If you don't want to take this step, just set

Action to take when anyone posts to the list from a domain with a DMARC
Reject/Quarantine Policy.
(Details for dmarc_moderation_action)

to "Munge From" and avoid the problem that way.

-- 
Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan