Exact response pattern
550 5.7.1 Rejected due to policy reasonsPermanentGMX/WEB.DEPolicy
What it means
The provider rejected the message under sender, authentication, reputation or content policy.
Likely causes
- Poor IP/domain reputation.
- Authentication issue.
- Unwanted content signals.
Recommended response
- Collect the full response.
- Check authentication and sender reputation.
- Use the provider postmaster channel after fixing the cause.
Operational rule: Preserve the complete SMTP response, remote hostname, sending IP, envelope sender and timestamp. Never diagnose from the three-digit code alone.