Exact response pattern
554 5.7.1 Sender rejected due to poor reputationPermanentCisco TalosReputation
What it means
A Cisco-backed filtering gateway rejected the sender because of its reputation score or policy.
Likely causes
- Spam complaints.
- Compromised infrastructure.
- New or low-volume IP with negative history.
Recommended response
- Review Talos reputation.
- Secure and clean the sender.
- Request investigation only after evidence supports recovery.
Operational rule: Preserve the complete SMTP response, remote hostname, sending IP, envelope sender and timestamp. Never diagnose from the three-digit code alone.