Level: Advanced
The full header of a received message contains the actual, detailed authentication results receiving servers evaluated, making it the most direct diagnostic source available.
Locate the Authentication-Results Header
This header, added by the receiving server, contains the actual pass or fail outcome for SPF, DKIM, and DMARC checks performed on that specific message, along with details on why any check failed.
Trace the Received Headers in Order
Reading the stack of Received headers from bottom to top reveals the actual path a message took through intermediate servers, useful for identifying where an unexpected hop or delay occurred.
Compare Results Across Multiple Test Sends
Sending test messages to accounts at different major providers and comparing their respective Authentication-Results headers reveals whether an issue is provider-specific or affects delivery universally.
Next step: Use the SeoWolf's Notepad to document the full headers and authentication results from your test sends as you work through a diagnosis.