I've noticed that Microsoft's systems fail intermittently to validate DNS lookups for DMARC, SPF, DKIM, and PTR records. Some users have become accustomed to trying again later to get their eMails through (which is not ideal).Although it doesn't happen very often, Microsoft's systems have been doing this since last year (and possibly earlier than that), and it doesn't seem to target any particular providers (e.g., a few of my clients with GMail accounts have asked me what the errors mean when they've received bounce-backs just like the one that you included). Feel free to send some test messages to [email protected] from that address if you want to confirm that your DKIM is working -- they'll be rejected if it isn't.
Oh, I know the DKIM is OK, I can send messages to myself and everywhere else and even usually Microsoft. I guess if they ask I'll have to remind them that sometimes free services are worth what you pay for them.
R's, John
We've been sending this person mail for years at an outlook.com.au address and nearly all of them have worked, including several today. 550,5.7.515,Access denied, sending domain ARXIV.ORG 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 Spf= Pass , Dkim= Fail , DMARC= Pass [SY8P300MB0731.AUSP300.PROD.OUTLOOK.COM 2026-05-08T18:21:38.150Z 08DEAD0640C37A36] [MW4PR04CA0059.namprd04.prod.outlook.com 2026-05-08T18:21:38.232Z 08DEACE91EBF534A] [MW1PEPF0001615B.namprd21.prod.outlook.com 2026-05-08T18:21:38.253Z 08DEACF5EA686851]
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