Send & Receive Issues

Fix Microsoft 365 Email Bounced: Sending IP Listed by SpamCop

WPS Content Manager Sep 28, 2026 869 views

Question details

Users need to resolve an issue where outbound emails fail to deliver because the server's IP is listed on a blocklist.

Fix Microsoft 365 Email Bounced: Sending IP Listed by SpamCop

Product: Microsoft 365
Device & OS: not provided
Scenario: Sending outbound emails to recipients using a Microsoft 365 business account.
Observed behavior: The email is rejected, and the sender receives a Non-Delivery Report (NDR) stating that the sending IP address is listed by SpamCop or another real-time blocklist.

Before you start

Ensure you have the complete Non-Delivery Report (NDR) saved, as the exact error codes and IP information within it are critical for support to investigate.

Solution 1Recommended

Open a Support Request with Microsoft 365

Because this involves Microsoft's shared outbound IP pools, the organization's Global Administrator must request an investigation and delisting from Microsoft Support.

Microsoft 365 uses shared IP pools for outbound email. If a compromised tenant sends spam, the shared IP may end up on a blocklist like SpamCop. End-users cannot delist these IPs; it requires backend investigation by Microsoft.

Log in to the Admin Center

Navigate to the Microsoft 365 admin center and sign in using an account with Global Administrator privileges.

Navigate to Support

Click on the 'Support' tab in the left-hand menu, then select 'Help & support' or 'New service request'.

Provide NDR Details

In the support ticket, include the complete bounce message (NDR), sending domain, affected recipient addresses, exact date and time, and the listed IP address.

Wait for Investigation

Submit the request. Microsoft Support will review the mail-flow logs, identify the source of the reputation problem, and coordinate the delisting process.

Open a Support Request with Microsoft 365

Reseller-Managed Tenants: If your Microsoft 365 subscription is provided through a third-party reseller, the administrator may need to contact the reseller directly to open the service request on your behalf.

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Frequently Asked Questions

Why is a Microsoft 365 IP listed on SpamCop?

Microsoft uses shared outbound IP pools for its tenants. Occasionally, spam sent by a compromised account in the same pool can cause the entire shared IP to be temporarily listed on real-time blocklists like SpamCop.

Can I delist the Microsoft 365 IP from SpamCop myself?

No. End-users and standard administrators cannot directly delist Microsoft's shared IPs from SpamCop. Microsoft Support must investigate the internal source of the spam and handle the delisting process.

What information is needed to report the email bounce to Microsoft?

You must provide the complete Non-Delivery Report (NDR), which contains the sending domain, recipient addresses, precise date and time of the failure, and the specific IP address that was blocked.

How long does it take to delist an IP from SpamCop?

Once Microsoft resolves the underlying spam issue originating from their network pool, SpamCop typically drops the IP from its blocklist automatically within 24 hours.

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