emails dont' go thorugh as "unauthorized addresses but they went through a few days ago. Waht changed and why?

Jill Vexler 0 Reputation points
2026-06-08T01:41:24.5366667+00:00

emails I have sent are not not going through because the email addresses are not recognized. How to override this?

Outlook | Outlook for mobile | Outlook for iOS | For education
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  1. AI answer

    2026-06-08T01:41:37.02+00:00

    The most likely cause is that the sending or receiving service has started rejecting the messages as unauthorized or spam, or your account is being blocked or restricted.

    Based on the provided information, check the following:

    1. Verify the exact error text
    • If the error mentions codes like 550, 553, or “relay prohibited/relaying denied,” the SMTP server is rejecting the message because it does not recognize the sender as authorized to send through that server.
    • This can happen if:
      • The SMTP authentication settings changed.
      • The outgoing server or port was changed.
      • The provider tightened anti‑spam or anti‑spoofing rules.
    1. Check if your address is being treated as a bad/blocked sender
    • If the NDR or postmaster message says something like “Access denied, bad outbound sender” or that the account is suspected of sending spam, the service may have blocked outbound mail from the account.
    • In that case, the mailbox may have exceeded sending limits or been flagged for spam‑like activity.
    • For work/school (Exchange Online), the admin must:
      • Secure the account (check for compromise).
      • Unblock the user on the Restricted entities page in the Microsoft 365 Defender portal so sending is restored.
    1. Check Outlook.com account health (for personal Outlook.com addresses)
    • If using Outlook.com behind Outlook/Outlook mobile, and messages suddenly stop being delivered:
      • Confirm the account is not blocked and that sign‑in is working.
      • Make sure cloud storage and mailbox are not full; if storage is full, messages are bounced and cannot be delivered.
    1. Review postmaster/“delivery failed” reports
    • When messages bounce, Outlook.com or the recipient’s system often sends a “delivery failed” or NDR from ******@outlook.com, postmaster@microsoft.com, or similar.
    • Open that report and scroll to the “Diagnostic information for administrators” section to see the precise reason (invalid recipient, blocked sender, size limits, etc.).
    • Correct the issue (fix the address, reduce attachment size, or contact the admin/provider if it indicates blocking or spam listing) and resend.
    1. There is no safe “override” for unauthorized or blocked sending
    • When a server rejects a message because the sender is not authorized or is blocked as spam, this is an intentional protection. It cannot be bypassed from the Outlook client.
    • The only way to restore delivery is to:
      • Fix account configuration (correct SMTP/auth settings).
      • Ensure the account is not compromised.
      • Have the admin or provider remove any outbound block or restriction.

    If this is a school or work account, contact the organization’s email administrator with the full text of the latest bounce message so they can check for:

    • Outbound spam blocks or “bad outbound sender” status.
    • Sending limits being exceeded.
    • Any new security policies that restrict who can send to which domains.

    References:

    AI-generated content may be incorrect. Read our transparency notes for more information.

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  2. Huy-K 13,985 Reputation points Microsoft External Staff Moderator
    2026-06-08T02:19:16.6033333+00:00

    Dear @Jill Vexler,

    To ensure I understand your request correctly and to support you as effectively as possible, I need more specific information from you:

    • Could you share a screenshot of the issue?
    • Are you using a personal or business/ school account?
    • Are all emails failing, or only emails sent to specific recipients/domains?
    • Does the issue occur in Outlook desktop, Outlook on the web, or mobile, or all of them?
    • Are other users in your organization/ school experiencing the same problem?
    • What is the exact issue message or bounce-back (NDR) you receive?
    • Are these internal recipients, external recipients, or both?
    • Have these email addresses worked previously without issue (you mentioned they did a few days ago)?
    • Are the affected recipients in a specific external domain (e.g., Gmail, another company)?

    The issue you are experiencing is not something you can override in Outlook itself. When mail suddenly starts failing after working a few days ago, it usually means the mail service or policy changed, not that Outlook “forgot” the address. The cause depends on the bounce/NDR code you received. Email nondelivery reports (NDRs) and SMTP errors in Exchange Online - Exchange | Microsoft Learn

    Your provided information will help me assist you more promptly and efficiently. I am looking forward to hearing from you.

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  3. EmilyS_726 27,215 Reputation points Volunteer Moderator
    2026-06-08T03:17:46.7066667+00:00

    Hello

    If your email is being marked as unauthorized addresses, it means the domain didn't have SPF, DKIM and/or DMARC set up or it was set up incorrectly.

    Are you the owner of your email address domain? If not, escalate this to your organization IT. They need to update these records accordingly.

    If it has been working until recently, perhaps they change service provider in the back end and forgot to update SPF and DKIM.

    Businesses/organizations these days can use multiple different services to send emails on behalf of their domains. A simple way to think about it: imagine you give your child’s school a list of people allowed to pick them up. If someone shows up and says they’re authorized but their name isn’t on the list, the school would treat them as unauthorized. If that person keeps showing up, the school may eventually refuse them entirely.

    In this case, SPF, DKIM, and DMARC are the records that keeps the “approved list" of services allowed to send emails on behalf of your domain. For high-volume senders, Microsoft now enforces these checks more strictly. Without proper setup, messages may not just be marked as unverified, they can be blocked outright.

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