I am working on verifying the proper authentication (SPF, DKIM, and DMARC) of my SMTP setup. I have noticed that in many cases when I view an emails headers in gmail (... > Show Original), the highlighted headers at the top might only show one of these authentication types. Then, in the "Authentication-Results" printed below, all three authentication types are listed. This discrepancy happens even if all three passed. What determines whether or not an authentication method is highlighted at the top of the page?
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