Exact response pattern
553 5.7.1 Sender address rejectedPermanentGenericSender
What it means
The server rejects the envelope sender or From identity.
Likely causes
- Unauthorized sender domain.
- Invalid sender.
- Anti-spoofing policy.
Recommended response
- Use an authorized sender.
- Verify SPF, DKIM and SMTP account sender permissions.
Operational rule: Preserve the complete SMTP response, remote hostname, sending IP, envelope sender and timestamp. Never diagnose from the three-digit code alone.