Email Authentication Essentials
Everything that proves your mail is really yours: the authentication overview, each of SPF, DKIM, and DMARC in depth, and the DNS records they live in.
36 guides
The Complete Guide to Email Authentication
How SPF, DKIM, DMARC, and the newer ARC and BIMI standards prove your mail is really yours, and why cold email fails without them.
What Is an SPF Record, and How Do You Set It Up?
SPF is a DNS record listing the servers allowed to send as your domain. Here is how it works, how to set it, and the mistakes that break it.
What Is DKIM, and Why Does It Matter for Cold Email?
DKIM cryptographically signs every message you send so receivers can prove it is really from you and was not altered. Here is how to set it up.
What Is DMARC, and Which Policy Should You Use?
DMARC tells receivers what to do when SPF or DKIM fails, and reports who sends mail in your name. Here is how to roll it out without blocking yourself.
DNS Records for Email: MX, PTR, SPF, DKIM, and DMARC
Every deliverability check starts in your DNS. Here is what each email record does, MX, PTR, SPF, DKIM, DMARC, and how they work together.
Google and Yahoo Sender Requirements, Explained
Google and Yahoo now enforce authentication, one-click unsubscribe, and a hard spam-complaint ceiling. Here is exactly what each rule asks of you.
Multiple SPF Records: Symptoms, Causes, and Safe Repair
A practical guide to multiple SPF records: evidence, safe checks, edge cases, and a controlled next step.
SPF Too Many DNS Lookups: How to Simplify a Record
A practical guide to spf too many dns lookups: evidence, safe checks, edge cases, and a controlled next step.
DMARC Aggregate Reports: How to Read rua Data
A practical guide to dmarc aggregate reports: evidence, safe checks, edge cases, and a controlled next step.
DMARC Forensic Reports: When fo Data Is Useful
A practical guide to dmarc forensic reports fo: evidence, safe checks, edge cases, and a controlled next step.
DKIM Selector Rotation: Planning a Safe Key Change
A practical guide to dkim selector rotation: evidence, safe checks, edge cases, and a controlled next step.
DMARC Alignment Failed: Read the From, Return-Path, and d= Values
A practical guide to dmarc alignment failed from return path dkim: evidence, safe checks, edge cases, and a controlled next step.
SPF Softfail, Neutral, and Permerror: What Each Result Means
A practical guide to spf softfail neutral permerror: evidence, safe checks, edge cases, and a controlled next step.
Email Authentication for Multiple Sending Services
A practical guide to email authentication multiple sending services: evidence, safe checks, edge cases, and a controlled next step.
BIMI Readiness Checklist Beyond the Logo
A practical guide to bimi readiness checklist: evidence, safe checks, edge cases, and a controlled next step.
Reverse DNS and PTR Checks for Shared Sending Infrastructure
A practical guide to ptr reverse dns shared sending: evidence, safe checks, edge cases, and a controlled next step.
Tracking Domain Authentication: CNAME Setup and Failure Modes
A practical guide to tracking domain cname setup email: evidence, safe checks, edge cases, and a controlled next step.
One-Click Unsubscribe Headers: Implementation and Testing
A practical guide to one click unsubscribe headers implementation: evidence, safe checks, edge cases, and a controlled next step.
Authentication Change Rollback Plan for Email Teams
A practical guide to email authentication rollback plan: evidence, safe checks, edge cases, and a controlled next step.
How DNS Propagation Affects Email Authentication Checks
A practical guide to dns propagation email authentication: evidence, safe checks, edge cases, and a controlled next step.
Email Authentication Inventory Template for Vendor Offboarding
A practical guide to email authentication vendor offboarding: evidence, safe checks, edge cases, and a controlled next step.
DMARC rollout from p=none to enforcement
A practical guide to dmarc p none to quarantine rollout: evidence, safe checks, edge cases, and a controlled next step.
DMARC subdomain policy sp= explained and tested
A practical guide to dmarc sp subdomain policy: evidence, safe checks, edge cases, and a controlled next step.
DMARC pct tag rollout: scope, testing, and limits
A practical guide to dmarc pct tag: evidence, safe checks, edge cases, and a controlled next step.
External DMARC report destination authorization
A practical guide to dmarc external reporting authorization: evidence, safe checks, edge cases, and a controlled next step.
SPF include versus redirect: choose the right composition
A practical guide to spf include vs redirect: evidence, safe checks, edge cases, and a controlled next step.
SPF HELO identity and null MAIL FROM troubleshooting
A practical guide to spf helo identity null reverse path: evidence, safe checks, edge cases, and a controlled next step.
DKIM body hash failure after a gateway or list rewrite
A practical guide to dkim body hash failed: evidence, safe checks, edge cases, and a controlled next step.
DKIM selector delegation for agencies and multi-tenant senders
A practical guide to dkim selector delegation: evidence, safe checks, edge cases, and a controlled next step.
Separate authentication for marketing and transactional subdomains
A practical guide to transactional marketing subdomain authentication: evidence, safe checks, edge cases, and a controlled next step.
Parked and unused domains: anti-spoofing authentication baseline
A practical guide to parked domain SPF DMARC: evidence, safe checks, edge cases, and a controlled next step.
DMARC alignment test matrix for SaaS custom From domains
A practical guide to saas custom from dmarc alignment: evidence, safe checks, edge cases, and a controlled next step.
Email authentication DNS records with DNSSEC: what to validate
A practical guide to dnssec email authentication records: evidence, safe checks, edge cases, and a controlled next step.
Authentication records for disaster recovery and secondary senders
A practical guide to email authentication disaster recovery sender: evidence, safe checks, edge cases, and a controlled next step.
Authentication evidence pack for a deliverability incident
A practical guide to email authentication incident evidence: evidence, safe checks, edge cases, and a controlled next step.
DKIM public-key record syntax and DNS truncation checks
A practical guide to dkim public key DNS syntax: evidence, safe checks, edge cases, and a controlled next step.