SPF vs DKIM vs DMARC: what each actually does

SPF vs DKIM vs DMARC: what each actually does
Framing line: most guides list all three and explain none. These pin down what breaks without each.

🚀 Deliverability
— Auth-trio breakdown — made the cut for the one-line mental model: SPF checks the envelope, DKIM signs the content, DMARC tells the receiver what to do when they disagree.
— SPF 10-lookup-limit warning — worth your time for the silent failure: too many includes and SPF just stops, no error.

🧪 Tests
— DKIM-key-length note — picked it because 1024-bit keys are now flagged; 2048 is the floor.
— DMARC p=none trap — earned its spot for the false comfort: monitoring mode protects nobody, it only reports.

Order of operations: SPF + DKIM first, then tighten DMARC to quarantine, then reject.
Saved you ~2 hours.