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Fix: SpamCop Blacklisted Microsoft 365 Outbound IP Address
Question details
Users are receiving spam rejection messages because a Microsoft 365 outbound IP address is listed on SpamCop or another real-time blocklist (RBL).
- Product
- Microsoft 365
- Device & OS
- not provided
- Scenario
- Attempting to send outbound emails to clients or partners, but the messages are bouncing back with a spam rejection notice.
- Observed behavior
- Emails fail to deliver, and users receive a bounce-back message (Non-Delivery Report) indicating that the sending IP is blocked by SpamCop.
Gather the complete, non-redacted bounce-back messages and email message headers, as support teams need these to identify the exact blocked sending IP address.
Submit a Service Request in the Microsoft 365 Admin Center
The most effective way to resolve a blacklisted Microsoft IP is to have Microsoft investigate their outbound IP pool and coordinate the delisting process.
Microsoft 365 uses a shared pool of outbound IP addresses. If another tenant abuses this pool, the IP may be flagged by SpamCop. Microsoft must investigate the abuse and request the delisting on behalf of all affected tenants.
Sign in to the Microsoft 365 admin center using an administrator account.
Navigate to the Support section on the left-hand menu and click on 'New service request'.
Explain that outbound emails are bouncing due to a SpamCop RBL listing. Paste the complete rejection message and the non-redacted message headers into the ticket.
Submit the request. Microsoft support will trace the IP, investigate the outbound pool, and coordinate with SpamCop to remove the IP from the blocklist.
Verify the IP with Your Hosting Provider
Sometimes the blacklisted IP actually belongs to your web or email hosting provider (such as Bluehost) rather than Microsoft.
Contact Microsoft 365 Business Support by Phone
If you are unable to access the admin portal to submit an online ticket, you can reach out to Microsoft via phone support.
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Frequently Asked Questions
Why is my Microsoft 365 outbound IP on a SpamCop blacklist?
Microsoft 365 uses a shared pool of outbound IP addresses. If another organization using Microsoft 365 sends spam using the same IP address, it can trigger a listing on SpamCop, which temporarily affects your legitimate emails as well.
Can I remove the IP from SpamCop myself?
No, end users typically cannot delist shared Microsoft IPs. Microsoft or the hosting provider that owns the specific IP must investigate the root cause of the spam abuse and coordinate the delisting directly with SpamCop.
Will asking recipients to add me to their safe-senders list fix this?
No. While a safe-sender list bypasses some local spam filters, it will not bypass an IP-level blocklist like SpamCop, which rejects the connection entirely before the individual email address is even processed.
What information is required to investigate a blocked IP?
Support teams require the complete, non-redacted bounce-back message (Non-Delivery Report) and the full email message headers. This allows them to trace the exact sending IP address and confirm ownership before requesting delisting.
