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Email Delivery Failure

Ronaldo Gomes Alves 0 Reputation points
2026-05-07T11:14:08.7866667+00:00

To the Microsoft Support Team,

Good morning.

I am writing to express our complete dissatisfaction with the current email blocking situation. We are a long-standing company in the hospitality industry with over 50 years of tradition, and we are currently facing a severe financial impact because we cannot receive emails from customers using Microsoft accounts (Outlook, Hotmail, Live).

Our domain/IP is currently flagged by Spamhaus, and Microsoft is honoring this block, which is causing an unjustified disruption to our legitimate business operations. It is unacceptable for an established enterprise to be penalized this way without a clear path to immediate resolution.

We demand an urgent review of our IP reputation within the Microsoft network. We are a legitimate business, and this blockage is causing us to lose bookings and damage our relationship with our clients daily.

We expect an immediate response and a definitive solution to restore our communications.

Regards,

[Moderator note: personal info removed]

Exchange | Exchange Server | Other
Exchange | Exchange Server | Other

A robust email, calendaring, and collaboration platform developed by Microsoft, designed for enterprise-level communication and data management.Miscellaneous topics that do not fit into specific categories.

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  1. kagiyama yutaka 3,430 Reputation points
    2026-05-07T12:32:55.1833333+00:00

    I think once Spamhaus tags ur IP, msft can’t undo it, so clean the src (logs/malw/SPF) and push the delist first… if mail still feels stuck, use a temp outbound IP while the msft edge‑cache drops, that’s the only path that acctuly moves it.

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  2. Gabriel-N 17,785 Reputation points Microsoft External Staff Moderator
    2026-05-07T12:05:34.8266667+00:00

    Please note that Q&A forum is a public platform, and moderators will modify the question to hide personal information in the description. Kindly ensure that you hide any personal or organizational information the next time you post an error or other details to protect personal data.

    Hello Ronaldo Gomes Alves

    I understand how overwhelming and impactful this situation must be, especially given how it affects your business operations and communication with your customers.

    However, I would like to clarify that this is a user-to-user support forum, and I do not have access to Microsoft’s internal systems or the ability to directly unblock domains or IPs.

    For your situation, since your domain/IP is flagged by Spamhaus, I believe the most important step is to address the issue from that side first. I recommend that you:

    • Go to the Spamhaus lookup page and check your domain/IP status
    • Review the reason for the listing
    • Follow their instructions to resolve the issue and request delisting

    Once the listing is removed from Spamhaus, email delivery to Microsoft services (Outlook, Hotmail, Live) should gradually improve.

    Additionally, you may also consider contacting Microsoft Support for further assistance: Contact Microsoft Office Support.

    I hope this information is helpful

    Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

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  3. AI answer

    2026-05-07T11:14:33.0666667+00:00

    To restore email delivery from Microsoft accounts (Outlook, Hotmail, Live) as quickly as possible, the following actions are required:

    1. Resolve the Spamhaus listing
    • Because the domain/IP is currently flagged by Spamhaus and Microsoft honors that block, the first and most critical step is to work directly with Spamhaus to remove the listing.
    • Follow Spamhaus’ delisting and remediation process (identify why the IP was listed, fix the underlying issue such as compromised systems, open relays, or poor list hygiene, and then request delisting).
    • Until Spamhaus removes the listing, Microsoft 365 and Outlook.com will continue to treat the IP as high risk.
    1. Check and improve sending reputation and configuration
    • Ensure that the IP and domain’s sending reputation is being actively managed. Microsoft 365 filtering considers factors such as:
      • Sending IP reputation
      • Domain reputation
      • Email authentication (SPF, DKIM, DMARC)
      • List accuracy and complaint rates
      • Message content
    • Confirm DNS is correctly configured, including:
      • Valid MX records for the domain
      • Correct SPF records that authorize the sending IPs
      • Proper reverse DNS (PTR) so that the IP does not appear as non-routable or misconfigured. Microsoft might not accept email from senders who fail a reverse-DNS lookup or who advertise themselves as private/non-routable IP ranges.
    1. Verify whether Microsoft has blocked the IP
    • If messages to Microsoft 365 recipients are bouncing with an NDR such as:
      • 550 5.7.606-649 Access denied, banned sending IP [x.x.x.x]; To request removal from this list please visit https://sender.office.com/ and follow the directions. then the IP is on Microsoft’s blocked senders list.
    • In that case, use the Office 365 Anti-Spam IP Delist Portal at https://sender.office.com to request removal from the Microsoft 365 blocked senders list, following the guidance in “Use the delist portal to remove yourself from the blocked senders list.”
    1. Follow NDR guidance and Microsoft 365 external-sender troubleshooting
    • Carefully follow any instructions included in the non-delivery reports (bounce messages) received when sending to Microsoft 365 or Outlook.com recipients.
    • Review the external-sender troubleshooting guidance for:
      • Managing IP and domain reputation
      • Handling new IP addresses and ramp-up behavior
      • Ensuring DNS and reverse DNS are correctly configured
    1. Coordinate with affected Microsoft 365 recipients
    • Ask key Microsoft 365 customers (those whose mail is being blocked) to:
      • Open a support ticket with Microsoft 365 Support on behalf of the organization, if needed. In some cases, Microsoft Support must work directly with the owner of the blocked IP address space for legal reasons.
    1. Use Outlook.com/consumer support if the issue involves Outlook.com mailboxes
    • If Outlook.com (Hotmail, Live, MSN, Outlook.com) addresses are specifically affected, use the Outlook.com sender support and troubleshooting options:
      • For Outlook.com deliverability issues, use the sender support form referenced in “Sender Support in Outlook.com” under “Troubleshooting tips for IT admins.”

    These steps together form the supported path to restore email delivery: fix the root cause that led to the Spamhaus listing, request delisting from Spamhaus, ensure proper DNS and authentication, and, if necessary, request delisting from Microsoft via https://sender.office.com and follow the NDR guidance.

    References:

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

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