5.7.511 Microsoft bounce: sending ip banned

What 5.7.511 means

The IP address you sent from was banned by Exchange Online, so mail from it is refused.

Message text

Access denied, banned sender

Common causes of 5.7.511

• Sending IP address was banned by Microsoft

How to fix 5.7.511

1. Check the sending IP with blocklist check to see which list it is on.
2. Request removal through Microsoft's delist portal, giving the full NDR code and the IP address.

Check your domain

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Have the full bounce message? Paste it into the bounce code lookup and it will match the code and the provider for you. Open the bounce code lookup.

How to read 5.7.511

The second part, 5.7.511, is an enhanced status code (RFC 3463 §2) written class.subject.detail. Class 5 is a Permanent failure (5xx): the command was rejected and the sender should not repeat it unchanged (RFC 5321 §4.2.1; RFC 3463 §2).. Subject 7 is security or policy: authentication, authorization or policy refused the message. The detail number refines the subject, and providers may define details of their own, which is why one code can read differently at Gmail, Microsoft and Yahoo.

Do not keep resending the same message: a permanent failure repeats until the cause is fixed. Correct the cause, then send a new message.

Official source: learn.microsoft.com. Last verified 2026-10-20.

Related guides

• How to create an SPF record (syntax and examples)
• How DKIM works and how to publish a DKIM record
• How to set up a DMARC record, from p=none to p=reject

Related codes

• 5.7.0 SMTP: security status
• 5.7.1 SMTP: delivery not authorized
• 5.7.23 SMTP: SPF validation failed
• 5.7.25 SMTP: reverse DNS failed
• 5.7.26 SMTP: authentication failed
• 5.7.27 SMTP: sender has null MX

FAQ

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