Exact response pattern
550 5.3.5 System incorrectly configuredPermanentGenericServer
What it means
The destination mail system reports a permanent configuration problem.
Likely causes
- Broken routing or service configuration.
Recommended response
- Recipient administrator must fix the system.
Operational rule: Preserve the complete SMTP response, remote hostname, sending IP, envelope sender and timestamp. Never diagnose from the three-digit code alone.