Undeliverable errors

Question

I've had two different people reach out today to tell me they have recieved 'undeliverable' errors after trying to email me today. Yesterday there was no issue and I have not made any changes to settings on my end. Images of errors they received below. Is the error on my end or theirs, and how do we fix this?

Answer 1

Both messages were rejected by Outlook.com before reaching your mailbox, so changing your Outlook settings will not fix them; each sender must give the complete bounce message to their email provider or domain administrator.

What each error means

1. First screenshot — AS9031519: Message lacks SPF/DKIM/DMARC Auth Records Outlook.com rejected the message because it did not find the required sender-domain authentication. SPF, DKIM, and DMARC are DNS-based controls that identify authorized mail servers and protect against spoofing. Microsoft requires correctly published records and alignment with the visible From domain in applicable cases.[^1^](https://support.microsoft.com/en-us/outlook/fix-ndr-error-550-5-7-515-in-outlook-com "Fix NDR error "550 5.7.515" in Outlook.com | Microsoft Support") Action for that sender:
   • If they use an ordinary personal Gmail address, they should report the full delivery failure to Google/Gmail support because they cannot change Gmail’s authentication records themselves.
   • If they use Gmail or another service with a custom business domain, their administrator must:
     1. Confirm the domain has one valid SPF record authorizing every service that sends its mail.
     2. Enable DKIM signing and publish the required DNS key.
     3. Publish a valid DMARC record.
     4. Confirm either SPF or DKIM aligns with the domain shown in the message’s From address.
     5. Retest delivery after DNS changes propagate.
   Microsoft has also received contemporaneous reports of sudden AS9031519 rejections involving Outlook.com recipients, so an Outlook.com filtering issue is possible, but it has not been established as a confirmed service-wide incident.^2^
2. Second screenshot — sending IP [IP Address] is on Microsoft’s block list This rejection concerns the outbound server operated by Vodien or its upstream provider—not your Outlook.com address. The sender should contact that provider and supply:
   • The complete bounce message.
   • Sending IP [IP Address].
   • The date and time of the failed delivery.
   • The Outlook.com rejection server and 550 5.7.1 response.
   The provider that controls the IP should investigate outbound abuse and submit the IP through Microsoft’s delisting process. If the sender controls the server/IP directly, the public delist portal is: https://sender.office.com Microsoft’s guidance for this same block-list response assigns the delisting action to the sending provider or IP owner.^3^

What to do on your side

• Do not change your password, mailbox rules, blocked-sender list, or storage settings for these errors. The messages were refused during the server-to-server SMTP exchange and never entered your mailbox.
• Ask both people to preserve and forward the entire original bounce, preferably as an attachment, to their respective providers. A screenshot can omit diagnostic fields needed for investigation.
• For urgent communication, ask them to use another email account or communication method while their providers resolve the rejection.
• Because two unrelated services failed on the same day, report the examples through Outlook.com: Help (?) → Help → Contact Support. Include both complete bounces and emphasize that they came from unrelated sending systems. This gives support enough information to investigate whether the authentication rejection is an Outlook.com false positive.
• Adding the senders to Safe senders is unlikely to help because these messages were rejected before mailbox-level junk filtering.

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References

1. Fix NDR error "550 5.7.515" in Outlook.com | Microsoft Support
2. Emails bouncing back to Microsoft emails - Microsoft Q&A
3. How to I contact Microsoft about Block List S3150 - Microsoft Q&A