How to Resolve Email or IP Address Spam-Filter Blocklisting
Question details
The user needs to resolve an issue where their email address or sending IP address is blocked by spam-filtering services, preventing message delivery.
- Product
- Email Services
- Device & OS
- not provided
- Scenario
- Sending emails to recipients on platforms like Hotmail or Outlook.com, resulting in blocked or rejected messages.
- Observed behavior
- Sent emails bounce back with rejection messages indicating that the sending IP or email address has been flagged by a spam filter.
Gather the exact bounce-back emails or Non-Delivery Reports (NDRs), including timestamps, affected domains, and your sending IP address, as support teams will need this data to investigate.
Open a Service Request in the Microsoft 365 Admin Center
If you are a Microsoft 365 user, your domain administrator must contact Microsoft Support to investigate your IP sending reputation and request a delisting.
Microsoft 365 maintains strict spam filters and sender reputation logs. If your outgoing IP or domain is flagged, only a Global Administrator can initiate the removal process.
Have your organization's Global Administrator navigate to the Microsoft 365 admin center and sign in with their admin credentials.
Click on the 'Support' or 'Help & support' icon located in the bottom right corner of the admin dashboard.
Open a new support ticket and provide the collected rejection messages, timestamps, sending IP addresses, and affected domains so the Microsoft team can investigate and clear the blocklist.
Contact Your Internet Service Provider (ISP)
If you do not use Microsoft 365, the spam blocklist might be triggered by your ISP's IP range or a local security breach.
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Frequently Asked Questions
Why was my email address or IP placed on a spam blocklist?
Blocklisting usually occurs due to a poor sender reputation, an account that was compromised and used to send spam, or because your Internet Service Provider's IP range was flagged for suspicious mass-mailing activity.
How long does it take to get removed from an email blocklist?
The removal timeframe varies by the service provider (like Microsoft or Spamhaus). Once you resolve the underlying security issue and submit a delisting request, it typically takes anywhere from a few hours to a couple of days.
What is a Non-Delivery Report (NDR)?
An NDR is an automated bounce message sent by the mail server informing you that your email could not be delivered. It contains critical diagnostic codes and IP information needed to appeal a spam filter block.
