Email & DNS guides
Plain-English explainers and step-by-step how-tos for email authentication and DNS. Start with the big picture, or jump straight to the fix you need.
How to check your domain with MXHelper (step-by-step)
A screenshot-by-screenshot tour of the full domain check: enter a domain, read the score, and fix what's flagged.
How to check an SPF record (and build one), step-by-step
Look up your SPF record, watch the 10-lookup limit, and build a correct record from a few clicks — with screenshots.
How to check a DMARC record, step-by-step
Look up your DMARC policy and decode every tag — what's set, what's missing, and how to fix it.
How to look up a DKIM record, step-by-step
Find your DKIM key even when you don't know the selector, and read what the result is telling you — with screenshots.
How to check if your domain or IP is blacklisted
Test your sending IP (or a whole domain) against the major blocklists and read the verdict — with screenshots.
How to read email headers (analyze the delivery path)
Paste raw headers to trace an email's path, spot slow hops, and read its authentication results — with screenshots.
SPF, DKIM & DMARC: the complete guide to email authentication
The big picture: how the three email-authentication records fit together, and the order to set them up in.
Why are my emails going to spam? 10 causes and how to fix them
A practical checklist for diagnosing and fixing deliverability problems when your mail keeps getting filtered.
How to set up DMARC: from p=none to p=reject, step by step
The staged rollout that gets you to an enforced policy without accidentally blocking your own legitimate email.
SPF records explained, with real examples
A field guide to SPF syntax: mechanisms, qualifiers, the lookup limit, and the mistakes that quietly break it.
DKIM explained: how email signing actually works
How cryptographic email signing works under the hood, and what the selector, key pair, and signature each do.
MX records explained: how email routing works
How mail finds your servers — priorities, backups, and the common MX mistakes that stop mail cold.
DNS record types explained: A, AAAA, CNAME, MX, TXT, NS, SOA & CAA
The record types you'll actually encounter, what each does, and when to reach for it.
BIMI explained: how to show your logo in the inbox
The standard that puts your logo beside your emails — and the DMARC and certificate hurdles to get there.
New to email authentication? Start here
Email deliverability comes down to three DNS records — SPF, DKIM, and DMARC — and most inbox problems trace back to one of them being missing or misconfigured. If you're not sure where to begin, read SPF, DKIM & DMARC explained first. It covers the whole picture: what each record does, how they work together through alignment, and the order to set them up in. Everything else here builds on that foundation.
How these guides fit together
Once you understand the basics, the deep-dive guides cover each record on its own. SPF records explained walks through the syntax, the mechanisms and qualifiers, and the 10-DNS-lookup limit that silently breaks so many records. DKIM explained covers the cryptographic signing that proves your mail is genuine and unaltered, and why selectors matter. When you're ready to lock down your domain against spoofing, how to set up DMARC gives you the safe, staged rollout from monitoring to full enforcement.
Just trying to fix a problem?
If your messages keep landing in the spam folder, jump straight to why are my emails going to spam? — a practical, ten-point checklist with a concrete fix for each cause, from authentication gaps to reputation and reverse DNS. Each guide links to the matching free tool so you can check your own domain as you read, and back to the full domain diagnostic when you want everything checked at once.
Want to check your own domain instead? Run a free full domain diagnostic — it tells you exactly which of these to fix.