How to analyze message header changes after provider updates?

Analyzing message header changes after provider updates reveals filtering implementation details. Headers include authentication results, spam scores, routing information, and other metadata showing how providers processed your message.

After suspected updates, send test messages and examine headers carefully. New header fields, changed spam score patterns, or different authentication handling may appear. These details illuminate what the update changed and how it affects classification.

Header analysis requires technical understanding of email standards and provider specific headers. Gmail's X-Google-DKIM-Signature, Microsoft's X-MS-Exchange-Organization headers, and similar provider specific fields contain diagnostic information. Documenting header patterns over time builds knowledge of how filtering evolves.