Exact response pattern
550 5.7.1 Delivery not authorized, message refusedPermanentGenericPolicy
What it means
The receiver refuses the sender, recipient or message under its security policy.
Likely causes
- Relay attempt.
- Blocklist or reputation.
- Authentication or alignment failure.
- Restricted recipient.
Recommended response
- Read the complete provider text.
- Verify authorization and authentication.
- Check reputation and delisting only after remediation.
Operational rule: Preserve the complete SMTP response, remote hostname, sending IP, envelope sender and timestamp. Never diagnose from the three-digit code alone.