SPF authentication
Authentication & Alignment · Critical priority · hard-fail gate
What it is
SPF lets the From/Return-Path domain authorize which servers may send its mail. A pass proves the sending IP is allowed.
How to fix it
Publish a single v=spf1 TXT record listing your sending IPs/includes and ending with -all or ~all.
This is a hard-fail gate. If it fails, Gmail / Yahoo / Outlook may junk or reject your mail regardless of everything else — so fix it first.
Check your email
See how your real email scores on this and every other deliverability factor.