SPF Explained
Authorize sending infrastructure without exceeding DNS lookup limits.
GuideDKIM Explained
Sign messages and align selectors with sending domains.
GuideDMARC Explained
Publish policy, alignment and aggregate reporting.
GuideReverse DNS and HELO
Align PTR, A records and SMTP identity.
GuideBIMI Basics
Prepare DMARC and brand assets for BIMI.
GuideAuthentication Troubleshooting
Diagnose SPF, DKIM and DMARC failures.
Guide