My sent Outlook emails have been undeliverable. How do I fix this?

Question

Some articles and comments I read said Microsoft flagged my email as a spam. But how do I fix this?

*Solved, thanks.

Answer 1

If your Outlook emails are being marked as undeliverable, it could be due to several reasons, including being flagged as spam. Here are some steps you can take to try to resolve the issue:

1. Check for Non-Delivery Reports (NDRs): If you received a bounce message, check it for specific error codes and follow any instructions provided. For example, if you see an error like 550 5.7.606-649 Access denied, banned sending IP, you may need to request removal from a blocked senders list.
2. Verify Recipient's Email Address: Ensure that the email address you are sending to is correct. Sometimes, a simple typo can cause delivery issues.
3. Check Your Email Configuration: Make sure your email settings are correct and that you are not advertising yourself as a non-routable IP. This can happen if your email server is misconfigured.
4. Contact Support: If the problem persists, consider reaching out to Microsoft support for assistance. They can provide more specific guidance based on your account and the issues you are experiencing.
5. Monitor Your Sending Behavior: If you have recently sent a large volume of emails, this could trigger spam filters. Try to limit your sending rate and ensure that your emails comply with best practices to avoid being flagged.

By following these steps, you should be able to identify and resolve the issue with your undeliverable emails.

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References:

• Fix NDR error "550 5.1.10" in Exchange Online
• External senders - Troubleshoot email sent to Microsoft 365

Answer 2

Hello, can you please share the bounce email? It contains important diagnostic data that helps shed some light of the root cause. Feel free to redact personal information when you share.