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Bounce codes › Microsoft 365

550 5.7.606: Access denied, banned sending IP

The IP address that sent your email is on Microsoft's block list. Codes 5.7.606 to 5.7.649 all mean this.

Fix your sending setup Your sending IP or domain is blocked

Microsoft banned the IP address you send from.

  • Sent by: Microsoft 365 / Outlook
  • Permanent (hard bounce). Sending the same message again fails again.

How Microsoft 365 words it (source):

Access denied, banned sending IP

Why it happens

  • The IP has a poor reputation: spam complaints, or many messages to addresses that do not exist.
  • The server was hacked or is an open relay.
  • A shared IP at your email service, spoiled by another customer.

What to do

  1. Ask for removal in Microsoft's delist portal (the bounce gives the link). You enter your email address and the IP.
  2. If the IP belongs to your email service, send them the bounce.
  3. Fix the cause first, or the IP will be listed again. Check your list before the next send.

Don't confuse it with

550 5.7.511 is also a banned IP, handled by email to [email protected]. 550 5.7.507 and 5.7.513 are blocks set by the recipient's company.

Questions

Is it my domain or my IP that is banned?

The IP address, shown in square brackets in the bounce.

Should I delete the bounced addresses?

No. They would bounce for any message from this IP.

Got a different bounce?

Paste the whole message into the bounce code lookup. It reads the code and the words and tells you whose move it is.

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