Content & Headers

Header Analyzer

Paste raw email headers and get a full analysis: hop map, auth results, latency per hop, alignment, and warnings.

About this check

Paste raw headers for hop map and auth breakdown.

Frequently asked questions

What does the Header Analyzer actually check?: Paste raw headers for hop map and auth breakdown.
Is this really free?: Yes. Every on.bo tool is free, no signup required, no rate-limit tricks.
Do you store the data I check?: We log minimal metadata to keep the service healthy. Lookups themselves are not retained beyond short-term caching.