What are SPF, DKIM, and DMARC?

They are three DNS records that prove your email is legitimate. SPF lists the servers allowed to send for your domain. DKIM cryptographically signs each message so the receiver can confirm it was not tampered with. DMARC tells the receiver what to do when SPF or DKIM fails, and gives you reporting.

Without all three, modern filters quietly route cold email to spam — no bounce, just silence — which is the hardest pipeline leak to diagnose. Set them on each sending domain, start DMARC at quarantine, and verify with mail-tester.com before sending.