Short answer
Look up the domain's TXT records. SPF is a TXT record starting v=spf1. DMARC is a TXT record on the name _dmarc followed by your domain. DKIM is a TXT record on a selector name followed by _domainkey and your domain, and you need the selector from your email provider. A DNS checker shows all three.
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What the three records do
SPF lists the servers allowed to send email for your domain.
DKIM adds a digital signature to each message, which receivers check against a public key published in DNS.
DMARC tells receivers what to do when a message fails SPF and DKIM, and where to send reports.
Together they are what mail providers look at to decide whether a message is real or spam.
How to look up SPF
Enter your domain into a DNS checker and open the TXT tab. The SPF record is the one that begins with v=spf1. It lists approved senders and ends with a rule for everything else.
You should have exactly one. Two SPF records make both invalid. Our DNS checker flags this directly.
Try it now: DNS Checker → · Email Deliverability Check →
How to look up DMARC
DMARC lives on a name made by putting _dmarc in front of your domain. Type that whole name into the DNS checker, for example _dmarc.yourdomain.com, and read its TXT record. It starts with v=DMARC1.
The p value is the policy. A value of none only monitors, quarantine sends failures to spam, and reject blocks them.
How to look up DKIM
DKIM sits on a name made from a selector, then _domainkey, then your domain. The selector is a label your email provider chose, and you cannot guess it. Find it in your provider's setup instructions, then type the full name into the DNS checker.
Mistakes that send email to spam
Two SPF records. An SPF record that does not include your email provider. A sending tool, such as a newsletter service, that was never added. No DMARC at all. A DMARC policy set to reject before SPF and DKIM are working, which blocks your own mail.
Most of these are invisible until mail starts disappearing, which is why checking the records is worth five minutes.
Checking the whole setup
Our email deliverability check reads SPF, DKIM and DMARC together and explains what each result means in plain English. Use the DNS checker when you want to see the raw records themselves.