550 5.7.511: Microsoft blocked your sending IP
Microsoft 5.7.511 means your sending IP is banned. Find the affected IP, check for abuse, and send Microsoft the full bounce to request removal.
Find the blocked IP
Read the full bounce and your sending provider's logs to identify the connecting IP. A shared provider may send several customers' mail through it, so the listing alone does not prove that your account caused the problem.
Check for abuse before requesting removal
Ask the operator of that IP to review outbound traffic, compromised accounts, and unsolicited mail. If you use a shared sending service, give its support team the complete bounce. Editing SPF or DKIM does not by itself remove an IP block.
Use the documented removal path
Send Microsoft the full non-delivery report and the sending IP at delist@microsoft.com. Keep any case reference and follow the response. Removal depends on Microsoft's review; repeated retries do not clear the listing.
Frequently asked
What does 550 5.7.511 mean?
Microsoft blocked the IP address connecting to its mail servers. The code alone does not establish that your email address or domain is banned.
How do I request removal?
Microsoft documents emailing delist@microsoft.com with the full non-delivery report and the sending IP. Follow any specific instructions in your bounce, and fix abuse or compromise before requesting removal.
How is 5.7.511 different from 5.7.606?
Both describe a sending IP block. Microsoft documents an email request for 5.7.511 and its self-service sender.office.com portal for the 5.7.606 through 5.7.649 range.
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Keep reading
Microsoft 5.7.606
Another Microsoft IP block, with self-service removal through sender.office.com.
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Last verified 2026-10-23 against Microsoft's non-delivery report reference.
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