Hi there, Since Monday 11:10am UTC, we see a huge rise of that SMTP answers with Outlook :
*550 5.7.515 Access denied, sending domain DOMAIN.TLD doesn't meet the required authentication level. The sender's domain in the 5322.From address doesn't meet the authentication requirements defined for the sender. To learn how to fix this see: https://go.microsoft.com/fwlink/p/?linkid=2319303 <https://go.microsoft.com/fwlink/p/?linkid=2319303> Spf= Pass , Dkim= Fail , DMARC= Pass [XXXXXX] [XXXXXXXXXX]* For that specific case, it seems that this bounce is triggered by the message and is not DNS related... We've seen this starting at the exact same minute on several senders (not all) with specific criteria : - French or Spanish language messages with accents in DKIM Signed Headers - Emojis in DKIM Signed Headers - The same FROM Header can send several messages, this SMTP answer will only appear on some specific messages with a bounce rate of 100% *It seems to be related to badly encoded characters* This does not mean that there is absolutely no DNS issue at all in any other cases, so this should not be related to issues prior to Monday June 16, 11:10am UTC... This SMTP answer is generic for all DKIM failures with Outlook, I'm just saying that we've seen that new pattern and the impact is quite huge Did anyone notice this pattern as well? Thanks, YM -- Postmastery *Email Infrastructure, Analytics and Deliverability* Amsterdam, NL / Paris, FR PHONE : +33 6 16 83 48 97 www.postmastery.com We welcome all (positive 😉) feedback at: https://www.trustpilot.com/review/postmastery.com Le mer. 18 juin 2025 à 00:02, Bradley King via mailop <[email protected]> a écrit : > > > > We are also observing similar issues for our customers sending mail to > Hotmail/Outlook/Live.com – basically all Microsoft domains. > > > > Loud shout out for anyone in MS here? > > > > -Thiyaga- > > > > We are seeing the same when sending to Outlook/Hotmail domains. > Commencing Jun 16 21:11:00(AEST : GMT+10). Their SMTP response includes: > > "Spf= Pass , Dkim= Fail , DMARC= Pass" > > Nothing changed with our DKIM records. > > Cheers, > > Brad > _______________________________________________ > mailop mailing list > [email protected] > https://list.mailop.org/listinfo/mailop >
_______________________________________________ mailop mailing list [email protected] https://list.mailop.org/listinfo/mailop
