How do you distinguish between technical vs reputation-based bounces?

Technical vs reputation bounces require different responses:

Technical bounce indicators:

DNS-related errors (host not found, MX lookup failed). Connection issues (timeout, refused). TLS/certificate problems. Protocol errors (syntax, sequence).

Reputation bounce indicators:

References to spam or content. Policy rejection language. Blocklist names or URLs. "Reputation" or "sender quality" mentions. Authentication failure references.

Code-based hints:

Technical: 4.4.x (network), 5.4.x (routing), 5.0.x (other). Reputation: 5.7.x (security/policy).

Why distinction matters:

Technical: Often temporary, may not be your fault, retry appropriate. Reputation: Your fault, requires sender-side remediation, address quality or configuration.

Technical problems are infrastructure issues. Reputation problems are behavior issues. Diagnosis determines treatment.