SPF Validation Error

W 30 Reputation points
2026-11-06T09:05:34.4733333+00:00

Dear Anna (https://learn.microsoft.com/en-us/answers/questions/5017083/spf-validation-error),

I need help because we suddenly received this error today and never received such an error before. Our server was working fine all along and suddenly it's getting blocked by you.

I tried to paste the email here but it keeps getting blocked by your automated deletion system, so please give me an email where I can send it to you.

Outlook | Windows | Classic Outlook for Windows | For business

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  1. Daniel-Vo 7,980 Reputation points Microsoft External Staff Moderator
    2026-11-09T08:24:19.91+00:00

    Hello @W  and everyone,

    Based on the information available to me, there is currently an ongoing Exchange service issue messages to Outlook.com, Hotmail.com, or Live.com addresses. Affected users may receive Non-Delivery Reports (NDRs) citing 550 5.7.1 or 550 5.7.23 errors related to SPF validation failures. This advisory is currently active and classified as a service degradation.

    Microsoft is actively investigating the underlying cause of this email delivery issue, and engineering teams are actively analyzing service telemetry and customer-provided data to identify the source of the issue. 

    I sincerely apologize for the inconvenience this ongoing issue may be causing. I understand how critical reliable email delivery is to your business operations, and I appreciate your patience while Microsoft works to identify the root cause and restore normal service as quickly as possible.

    If you continue to experience this issue, please contact Microsoft Support Team and provide fresh Network Message IDs, relevant message logs, and examples of affected messages in .eml format so that they can be included in the investigation.

    For business support:   

    1. Find your Microsoft 365 admin: If you're not an admin and don't know who the admin is in your organization, you can find guidance here: How can I find my Microsoft 365 admin? - Microsoft Support    
    2. Submit a service request: The Global Administrator should create a support request with Microsoft to receive advanced technical assistance. For detailed instructions, see: Get support - Microsoft 365 admin | Microsoft Learn    

    Note: If your subscription is from a partner or reseller, contact the reseller's support provider to help open a service request on behalf of you instead.    

    Thank you again for your understanding. I’ll provide additional updates as soon as more information becomes available.

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    10+ people found this answer helpful.
  2. M S 0 Reputation points
    2026-11-09T11:48:42.0866667+00:00

    This is causing me a huge amount of issues and its a shame that Microsoft or Outlook are taking so long to fix this.

    Numerous people who have been sending me e-mails for years are recently reporting that when sending e-mails to my @live.com e-mail account, they receive a error message

    550 5.7.1 Message rejected: Message lacks SPF/DKIM/DMARC Auth Records (AS9031519).

    I can't start telling my accountant, my lawyer, my wife and many other people to change their IP settings but rather Microsoft / Outlook has to revert a recent change they must have made !!

    Which department is responsible for this ? Its been going on for days and causing huge damages !

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    2 people found this answer helpful.
  3. GTS-NJ 1,250 Reputation points Volunteer Moderator
    2026-11-07T16:34:54.5133333+00:00

    Microsoft Outlook SPF validation error blocks email sending and receiving

    https://www.neowin.net/news/microsoft-outlook-spf-validation-error-blocks-email-sending-and-receiving/

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    1 person found this answer helpful.
  4. Nik 0 Reputation points
    2026-11-08T05:12:13.03+00:00

    Same issue. Had the same SPF details etc and now suddenly emails are being blocked (seems to be outlook users). What on earth do we do to fix this???

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  5. Daniel-Vo 7,980 Reputation points Microsoft External Staff Moderator
    2026-11-06T10:33:29.6733333+00:00

    Hi @W ,

    I understand how frustrating this must be.

    Firstly, I would like to clarify that this is a public forum, so please avoid posting the entire email, message content, or any personal information. To prevent the post from being automatically blocked, please share only the relevant error details first.

    The 550 5.7.23 error typically indicates that the sending IP address is not authorized by the domain's SPF record or that SPF validation failed during message authentication.

    If you're encounter this error, the steps below may help:

    Please note that these changes must be performed by the email or domain administrator, as they typically require access to DNS records and mail server configuration. If you're not the administrator and don't know who the admin is in your organization, you can find guidance here: How can I find my Microsoft 365 admin? - Microsoft Support    

    1. Verify that the sending domain has a valid SPF record published in DNS.
    2. Confirm that the IP address or mail service actually sending the messages is included in the SPF record. This includes any on-premises mail servers, SMTP relays, bulk mail providers, CRM systems, or third-party email gateways.
    3. Ensure that only one SPF record exists for the domain, as multiple SPF records can cause SPF validation failures.
    4. Check that the SPF record does not exceed the SPF limit of 10 DNS lookups.
    5. If messages are routed through a third-party gateway or filtering service, verify that SPF evaluation is being performed against the correct originating sender and that the gateway is configured appropriately.
    6. If applicable, verify that DKIM and DMARC are also configured correctly, as mail authentication issues can sometimes involve multiple authentication methods.
    7. After making any DNS changes, allow time for DNS propagation and then retest message delivery

    If the issue persists after the above checks, please contact Microsoft Support for further investigation, as additional backend analysis may be required. Their specialists can perform deeper diagnostics and, if needed, escalate the case to the appropriate internal team for further analysis. This ensures the issue is formally tracked and may contribute to a future fix.   

    For business support:   

    • Submit a service request: The administrator should create a support request with Microsoft to receive advanced technical assistance. For detailed instructions, see: Get support - Microsoft 365 admin | Microsoft Learn    
    • If your subscription is from a partner or reseller, contact the reseller's support provider to help open a service request on behalf of you instead.

    If you discover any solutions or have additional insights, please consider replying to this thread to help others in the community.   

    I sincerely apologize for redirecting you to the Microsoft Technical Support Team. While I strive to assist as much as possible here in the forum, my resources are limited when it comes to backend-level diagnostics and advanced troubleshooting. Some issues require deeper technical analysis and access to internal tools that only the official support team can provide.    

    For your reference: Fix NDR error 5.7.23 in Exchange Online - Exchange | Microsoft Learn 

    If you need further assistance, feel free to reply. I'm here and happy to help!

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