SMTP code 4.7.X
What the knowledge base's own tables say about this code, and which articles say it — a description of the reply, never a placement prediction.
The knowledge base documents this code in more than one row. What tells those rows apart is the rejection text in your own log, not the code: read each line below against what your rejection says.
- Meaning
- Temporary deferral for policy reasons (greylisting, rate limiting, "unusual volume")
- Next step
- Slow down. This is the classic throttling signal during warm-up
From SMTP Enhanced Status Codes (RFC 3463) · Using the codes for bounce classification
- Test that tells causes apart
- See Playbook B
- Next step
- Slow down. See MTA delivery tuning
- Rejection says…
- "too many messages", or rate or connection language (421, 4.7.x, which is technically a deferral)
- Hypothesis
- Rate limiting
From Delivery Troubleshooting Playbooks · Playbook A: message not delivered (bounced or rejected, 5xx)