[outages] yahoo

[Cary Wiedemann]

Okay, just resolved this from my end. My O365 emails were being DKIM signed
but by our .onmicrosoft.com subdomain instead of the actual sending
domain.  Headers would show dkim=pass but the DKIM domain didn't match the
FROM address in our envelopes.

Had to enable DKIM signing on the custom domain in O365 here
https://security.microsoft.com/authentication?viewid=DKIM and setup CNAMEs
for the proper selectors in DNS.

DMARC reports from Yahoo helped me a ton here, but they were confusing.
They showed DKIM failed in the policy_evaulated -> disposition section but
showed result = pass in the auth_results -> dkim section.

Just had my first successful email to Yahoo.com in days.  Looks like the
O365 DNSRBL inclusion was a red herring.

- Cary

On Mon, Mar 11, 2024 at 1:34 PM Cary Wiedemann <carywiedemann at gmail.com>
wrote:

> Massive problems with email delivery to Yahoo and AOL today, they share a
> mail system on the back-end.  Microsoft issued advisory EX719348 last
> Thursday for their IPs being included in some DNSRBLs, and I still see some
> of their IPs on the Spamhaus RBL (40.107.102.127) but I'm not sure if
> that's the root cause.
>
> All my emails from O365 to Yahoo and AOL have been failing since 3/7.
>
> Lots of noise and confusion because Yahoo and AOL recently started
> enforcing stricter SPF/DKIM/DMARC requirements, but this seems to be
> unrelated.  These emails are DKIM signed, pass SPF, and have a valid DMARC
> record.
>
> Still investigating, will update the list with the eventual resolution.
>
> - Cary
>
> On Mon, Mar 11, 2024 at 1:27 PM bannereddivpool via Outages <
> outages at outages.org> wrote:
>
>> Anyone seeing any issues with yahoo email services?  I keep getting
>> dropped;
>>
>> telnet  mta6.am0.yahoodns.net 25
>> Trying 67.195.204.74...
>> Connected to mta6.am0.yahoodns.net.
>> Escape character is '^]'.
>> 220 mtaproxy501.free.mail.bf1.yahoo.com ESMTP ready
>> EHLO mail.yahoo.com
>> 250-mtaproxy501.free.mail.bf1.yahoo.com
>> 250-PIPELINING
>> 250-SIZE 41943040
>> 250-8BITMIME
>> 250 STARTTLS
>> Connection closed by foreign host.
>>
>> Sending from outlook and I'm getting this as well;
>>
>> *Diagnostic information for administrators:*
>>
>> Generating server: SJ2PR14MB6550.namprd14.prod.outlook.com
>> Total retry attempts: 7
>>
>> sample1 at yahoo.com <babyereed2013 at yahoo.com>
>> Remote server returned '550 5.4.300 Message expired -> 451 [RL01] Message
>> temporarily deferred'
>>
>> sample2 at yahoo.com <jbliqemp at yahoo.com>
>> Remote server returned '550 5.4.300 Message expired -> 451 [RL01] Message
>> temporarily deferred'
>>
>> Original message headers:
>> _______________________________________________
>> Outages mailing list
>> Outages at outages.org
>> https://puck.nether.net/mailman/listinfo/outages
>>
>
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