If your business sends emails, there is a good chance someone has tried to fake them. DMARC (Domain-based Message Authentication, Reporting and Conformance) is a DNS record — a small text entry attached to your domain name — that tells receiving mail servers what to do when an email claims to be from you but fails authentication checks. This guide explains how to check DMARC is set up for your domain, how to add it if it is missing, and what to do if something looks wrong.

Before you start

• You will need access to your domain’s DNS settings — usually via your domain registrar (such as GoDaddy, 123-reg or Cloudflare) or your hosting provider’s control panel.
• If someone else manages your DNS, have the domain name ready and ask them to follow the steps below.
• No special software is needed. A browser is enough.

How to check DMARC is set up

Option 1 – DIY

1. Open a browser and go to MXToolbox DMARC Lookup — a free, public tool for reading DNS records.
2. Type your domain name into the search box (for example, yourbusiness.co.uk) and press Enter or click DMARC Lookup.
3. Read the result. If DMARC is present, you will see a line beginning with v=DMARC1. Note the p= value — this is your policy. p=none means monitoring only; p=quarantine sends suspicious mail to spam; p=reject blocks it outright.
4. If the tool returns "No DMARC record found", your domain has no DMARC protection. Continue to the next section.
5. If the record exists but shows p=none, your domain is being monitored but unauthenticated emails are still being delivered. Consider tightening the policy once you have reviewed the reports.

Option 2 – Our Free Tool Will Check

Just pop in your email address below and our free to use tool will check your DMARK record for you:

How to add a DMARC record if one is missing

Why DMARC needs SPF and DKIM too

DMARC works alongside two other DNS records. SPF (Sender Policy Framework) lists the mail servers allowed to send on your behalf. DKIM (DomainKeys Identified Mail) adds a digital signature to outgoing messages. Without both in place, DMARC cannot authenticate your emails properly. The National Cyber Security Centre publishes plain-English guidance on all three and is worth bookmarking.

If you are not sure whether SPF or DKIM are configured, MXToolbox has free lookup tools for those too — search for MXToolbox SPF Lookup and MXToolbox DKIM Lookup.

How to check DMARC is set up correctly — a quick summary

To confirm everything is working: your DMARC lookup shows v=DMARC1; your SPF record starts with v=spf1; your DKIM lookup returns a valid public key. All three need to pass before you should consider moving from p=none to p=quarantine or p=reject.

If that did not work

• If the record still does not appear after 48 hours, clear your browser cache and try the lookup again, or use a different DNS checker such as Google Admin Toolbox.
• If your registrar panel does not allow you to add TXT records, contact your registrar’s support team — this is a standard DNS feature and they should be able to enable it.
• If you are receiving error messages about duplicate or conflicting DMARC records, delete any existing _dmarc entries before adding a new one.

When to ask us

If your domain is actively being used to send phishing emails to your customers or staff, or if the same DNS misconfiguration is showing across several of your company domains, that needs a technician rather than a self-serve fix. Computer Care customers can raise a support ticket and we will take it from there.