What’s the difference between authentication fail vs reputation fail in Postmaster?

Authentication failures in Postmaster Tools indicate technical problems with SPF, DKIM, or DMARC. Your messages failed to prove their claimed identity. Fixing these requires DNS configuration changes or infrastructure adjustments.

Reputation failures occur when authenticated messages still face filtering because of poor sender trust. The message proved who it was from, but Gmail does not trust that sender based on historical behavior.

Authentication is a prerequisite. Without passing authentication, you cannot build reputation. But passing authentication alone does not guarantee inbox placement.

Diagnose by checking both sections in Postmaster Tools. Authentication failures show configuration problems. Reputation failures show behavioral problems.

Authentication proves your ship is who it claims to be. Reputation determines whether that captain is welcome. You need valid papers before the harbor considers your track record, but papers alone do not earn trust.