Exact response pattern
452 4.5.3 Too many recipientsTemporaryGenericRate limit
What it means
The receiver limits the number of RCPT commands per transaction.
Likely causes
- Recipient batch too large.
Recommended response
- Lower max recipients per message transaction.
Operational rule: Preserve the complete SMTP response, remote hostname, sending IP, envelope sender and timestamp. Never diagnose from the three-digit code alone.