Exact response pattern
421 4.7.0 Temporary system problem. Try again laterTemporaryGenericPolicy
What it means
The provider is temporarily deferring traffic, commonly because of rate, reputation or policy signals.
Likely causes
- Volume increased too quickly.
- Poor recent reputation.
- Complaint or bounce signals.
- Too many parallel connections.
Recommended response
- Reduce concurrency and hourly rate.
- Preserve retries.
- Review authentication, complaints and recent list changes.
- Recover gradually after acceptance improves.
Operational rule: Preserve the complete SMTP response, remote hostname, sending IP, envelope sender and timestamp. Never diagnose from the three-digit code alone.