How do I get an IP removed from Microsoft's banned list?

Submit it at sender.office.com. You will receive an email asking you to confirm, then a decision. Most clean IPs are removed within 24 hours. Repeated listings get slower and eventually require a manual review with evidence of the fix.

Does 5.7.606 affect Outlook.com addresses too?

The ban lists for consumer Outlook.com and for Microsoft 365 are separate systems but share signals. A 5.7.606 from a tenant often comes with S3140 bounces from outlook.com at the same time.

Can I just send from another IP?

Only if the abuse is really stopped. Microsoft bans ranges when adjacent IPs start sending the same traffic, so moving without fixing the cause makes things worse.

550 5.7.606 Access denied, banned sending IP

The sending IP is on Microsoft's blocklist for Microsoft 365 recipients. It is the Exchange Online Protection counterpart of Outlook.com's S3140. The message is refused for every tenant until the IP is delisted, and the reply tells you where to apply.

What the server replies

550 5.7.606 Access denied, banned sending IP [203.0.113.10]. To request removal from this list please visit https://sender.office.com/ and follow the directions. For more information please go to http://go.microsoft.com/fwlink/?LinkID=526655 AS(1410) [SN1NAM02FT012.eop-nam02.prod.protection.outlook.com]

Sent by: Microsoft 365
Type: PermanentRetry fails
About: Reputation and blocklists
Enhanced code: 5.7.606

Who sends it

Exchange Online Protection at connection or MAIL FROM, for mail from an IP Microsoft has banned. It affects mail to any Microsoft 365 hosted domain, not only outlook.com addresses.

Why it happens

Spam or phishing was sent from the IP, often by a compromised account or a web form abused as a relay.
The IP is new to sending and jumped straight to volume, which Microsoft reads as a spam run.
Reputation inherited from a previous tenant of the IP.
Repeated delivery attempts to addresses that do not exist in Microsoft tenants.

How to fix it

Find and stop the abuse
Check the outbound queue and logs for the hours before the first bounce. Look for a single account or script with unusual volume, and disable it.
Submit the delist request
Use the sender support portal at sender.office.com with the exact IP. Automated removals are usually processed within a day; if the form says the IP is not eligible, Microsoft still sees abuse from it.
Prepare the IP for the retry
Confirm the PTR record, SPF and DKIM before mail resumes. A delisted IP with no authentication is relisted faster than it was removed.
Enrol in SNDS
Microsoft's Smart Network Data Services shows complaint rates and trap hits per IP so the next problem is visible before it becomes a ban.

Check it yourself

These free tools show the records and connections behind this code for your own domain or server.

Related codes

Sources

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