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550 5.4.1 Recipient address rejected: Access denied

permanent Policy

Meaning

The receiving server (typically Microsoft 365) rejected the message because the recipient address does not exist in its directory, blocking it at the edge.

Common causes

  • The recipient's email address is invalid or misspelled.
  • The recipient's organization has a misconfigured domain or directory synchronization issue in Microsoft 365.
  • The recipient's domain is configured as Authoritative but the user hasn't been created.

How to fix

  1. Verify the recipient's email address is correct.
  2. If the address is correct, the issue is on the recipient's IT side (Directory-Based Edge Blocking misconfiguration). You cannot fix this from the sender side.
  3. Remove the address from your list if you cannot verify it.

Provider notes

Microsoft 365. Generated when Directory-Based Edge Blocking (DBEB) in Exchange Online blocks an incoming email message because the recipient's email address doesn't exist.

Example bounce

550 5.4.1 Recipient address rejected: Access denied.

FAQ

Is this a spam block?
No, despite saying 'Access denied', 5.4.1 is almost always a routing or directory issue indicating the user doesn't exist, not a reputation block.
How should I handle this bounce?
Treat it as a hard bounce (user unknown) and suppress the address.

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