False IP reputation status

Question

Although we have successfully used the Office 365 Anti-Spam IP Delist Portal, the issue reappears after some time, which indicates a possible network-range or reputation false positive rather than a single-incident block.

Sending infrastructure details:

Public Sending IP: 84.205.225.118

Sending Hostname: mail.attikonhospital.gr

Sending Domain: attikonhospital.gov.gr

Our DKIM/SPF configuration is valid and outbound mail is authenticated. No abnormal traffic or spam campaigns have been detected on our side.

 

We kindly request:

1.      Review of the reputation status for the specific IP and its network range.

2.      Investigation of possible SmartScreen / Protocol Filter Agent false positives.

3.      Assistance toward a permanent resolution, as repeated delisting is only a temporary workaroun

Answer 1

If you are experiencing repeated issues with your IP address being blocked despite using the Office 365 Anti-Spam IP Delist Portal, it may indicate a broader issue with the reputation of your IP or network range. Here are some steps you can consider:

1. Monitor Your IP Reputation: Regularly check the reputation of your sending IP address using various IP reputation services. This can help identify if your IP is being flagged frequently.
2. Review Email Sending Practices: Ensure that your email sending practices comply with best practices to avoid being flagged as spam. This includes maintaining a clean mailing list, ensuring proper DKIM/SPF configuration, and avoiding sudden spikes in email volume.
3. Investigate Network Range: If your IP is part of a larger network range, it may be beneficial to investigate the reputation of the entire range. Sometimes, other users within the same range can negatively impact the reputation of your IP.
4. Contact Microsoft Support: Since you are looking for a permanent resolution, consider reaching out to Microsoft Support directly. They may be able to provide insights into why your IP is being flagged and assist in resolving the issue more permanently.
5. SmartScreen and Protocol Filter Agent: If you suspect that SmartScreen or the Protocol Filter Agent is incorrectly flagging your emails, you may want to provide feedback to Microsoft regarding these false positives. This can help improve their filtering systems.

Unfortunately, as an external sender, your options may be limited, and direct intervention from Microsoft may be necessary to resolve ongoing issues with IP reputation.

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References:

• External senders - Use the delist portal to remove yourself from the blocked senders list and address 5.7.511 Access denied errors
• External senders - Troubleshoot email sent to Microsoft 365