Senders receiving mail delivery failure attempting to send me email

Heidi Steeves 0 Reputation points
2026-11-07T20:37:48.9366667+00:00

Could someone please let me know how to resolve this?

Subject: Mail Delivery Failure

This message was created automatically by the mail system (ecelerity). A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed: >>> ******@hotmail.com (reading confirmation): 550 5.7.1 Message rejected: Message lacks SPF/DKIM/DMARC Auth Records (AS9031519) [CPH1EPF00000521.eurprd05.prod.outlook.com2026-11-07T18:56:58.938Z 08DF3B8A96F414C5]

Outlook | Web | Outlook.com | Email
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  1. AI answer

    2026-11-07T20:38:48.66+00:00

    The sender or their email provider must correct the sending domain’s SPF, DKIM, and DMARC configuration; there is no SPF, DKIM, or DMARC setting to change on your personal Hotmail mailbox.^1^

    What to do

    1. Ask the sender to forward the complete delivery-failure report to their email administrator or provider. Include the complete rejection text, especially:
      • 550 5.7.1
      • Message lacks SPF/DKIM/DMARC Auth Records
      • AS9031519
      • The Microsoft server name, timestamp, and message identifier
    2. The sender’s administrator should check the domain shown in the message’s From address. They need to verify that: Microsoft’s authentication troubleshooting guidance recommends fixing SPF first when the source is unauthorized, then DKIM, and finally verifying DMARC alignment.^3^
    3. After the sender changes DNS or mail-service settings, have them send a new test message. Retrying the original message without correcting authentication is unlikely to help.

    What will not resolve this

    • Adding the address to Safe senders
    • Checking Junk Email
    • Changing Outlook apps, browsers, or devices
    • Adding authentication records for hotmail.com yourself

    The message is rejected by Microsoft’s inbound servers before it reaches your mailbox, so mailbox-level safe-sender settings generally cannot override this authentication failure.^1^

    If more than one unrelated sender is affected

    If failures occur from several unrelated companies or email providers:

    1. Obtain the complete non-delivery report from each sender.
    2. Sign in to Outlook.com in a browser.
    3. Select Help (?) at the top of the page.
    4. Search for the error, then select Still need help? or Contact Support and submit the reports.

    Signing in before opening the Help pane is required for the Outlook.com support options to work.^4^

    If only one company or domain is failing, resolution remains with that sender’s administrator or email provider. As a temporary workaround, ask the sender to use a different, properly authenticated email account.

    References

    1. Incoming emails being blocked due to lack of SPF/DKIM/DMARC records on my @outlook.com account - Microsoft Q&A
    2. Fix NDR error "550 5.7.515" in Outlook.com | Microsoft Support
    3. Troubleshoot email authentication in Microsoft 365
    4. Fixes or workarounds for recent issues on Outlook.com | Microsoft Support
    AI-generated content may be incorrect. Read our transparency notes for more information.

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  2. EmilyS726 278.8K Reputation points Independent Advisor
    2026-11-07T21:13:46.7933333+00:00

    Hello

    I am seeing a sudden increase in similar reports from other users in this forum as well.

    Unfortunately, I cannot find any official information from Microsoft acknowledging this issue. Microsoft's published requirements for SPF, DKIM, and DMARC apply to senders sending more than 5,000 emails per day. However, based on the sudden increase in reports yesterday, I suspect these requirements may now be affecting low-volume senders as well. This is just my observation, not something Microsoft has officially confirmed.

    I helped several users with this issue yesterday in this forum. One interesting thing we noticed is that email headers may show DMARC as passing, even when the sending domain does not have a published DMARC record. We were able to identify this by checking the domain using a free tool such as https://mxtoolbox.com/.

    In some cases, once the missing DMARC record was properly configured and verified, emails started coming through again.

    For this reason, I strongly recommend having the sender check their SPF, DKIM, and DMARC records for the affected sending domains. Another useful tool is https://dmarcian.com/domain-checker/.

    If you need help checking these records, I am happy to do so. I would just need to know the sending domain name. You do not need to share the full email address.

    For now, verifying and correcting these authentication records is the best troubleshooting step I can recommend until Microsoft provides more official information. But this needs to be done on sender's side. There's nothing you can do on your side as recipient.

    If they are already configured correctly, but their emails are still being rejected when sending to Outlook.com or Hotmail.com users, you can tell them to send a report through Microsoft's sender support form. This will help bring the issue to Microsoft's attention.

    https://go.microsoft.com/fwlink/?LinkID=614866

    Also, news article about this issue: https://www.neowin.net/news/microsoft-outlook-spf-validation-error-blocks-email-sending-and-receiving/

    Note: These are non-Microsoft websites. They appear to provide useful information, but be cautious of advertisements or downloads for potentially unwanted software. You do not need to download anything to use the domain-checking tools.

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    1 person found this answer helpful.

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