How to identify unclassified bounces in ESP logs?

Identifying unclassified bounces improves your dictionary:

Finding unclassified entries:

Filter for "unknown" or "other" bounce category. Look for generic classifications. Search for bounces without enhanced codes. Review those marked "needs review."

Analysis approach:

Extract raw SMTP response. Identify provider from domain or MTA. Look for patterns in message text. Check for non-standard codes.

Common unclassified sources:

New or uncommon providers. Custom error messages. Foreign language responses. Legacy or misconfigured servers.

Improvement process:

Analyze unclassified bounces regularly. Create rules for recurring patterns. Add to bounce dictionary. Reduce unclassified percentage over time.

Unclassified bounces are gaps in your knowledge. Each one analyzed improves future handling.