Microsoft mail servers 550 5.7.124
Recipient policy
Recipient policy means the receiving provider rejected the message for a provider-specific reason. Use the diagnostic text before deciding on retries or suppression.
Decision
Do not retry unchanged. Fix the sender setup first.
Confidence: high. Recipient validity: valid.
Match this reply
- SMTP stage
- RCPT TO recipient check
- Endpoint
- Inbound MX
Sender not in allowed-senders listUse tools
Start here
- 1
Ask the recipient or group owner to allow external senders or add the sender to the allowed list.
- 2
Do not suppress the address as invalid unless the bounce explicitly says the mailbox does not exist.
Confirm the cause
- Ask the recipient or group owner whether external senders are allowed.
- Confirm the sender address or domain is on the recipient's allowed-senders list if one is required.
- Retry only after the recipient-side policy has changed or the sender has been allowed.
App handling
- Treat this as a sender setup incident, not a bad recipient.
- Hold similar mail for the same sender domain or provider until the fix is verified.
- Retry after a fresh single-recipient test succeeds.
Avoid
- Do not retry unchanged in a loop.
- Do not suppress the recipient unless the text explicitly says the mailbox is invalid.
- Do not treat a permanent SMTP code as proof that the address is bad; policy and routing failures can also be permanent.
Common causes
- The recipient or group blocks external senders.
- The sender is not on the allowed-senders list for that mailbox or group.
- A recipient-side admin policy rejects this sender before mailbox delivery.
Developer details
Fields to log
raw SMTP replyremote MX or hostSMTP stagereply codeenhanced codeprovidermatched rule idrecipientsending domaindecisiontimestampenvelope recipientcontact id
Classifier evidence
- Specific cause
- group sender not allowed
- Evidence
- official