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Email Deliverability Checker: SPF, DKIM and DMARC for your domain

Check SPF, DKIM, DMARC and MX against the Gmail, Yahoo and Outlook.com sender rules.

  • Free to use
  • Nothing to install
  • No sign-up

How to use the Email Deliverability Checker

Read what the guide says

This is the Email Deliverability Checker.

It checks SPF, DKIM, DMARC and MX against the Gmail, Yahoo and Outlook.com sender rules.

Gmail asks every sender for SPF or DKIM.

If mail goes to spam, it checks one common cause: missing or broken authentication.

Type the domain you send email from.

Here, it's a sample domain for a made-up dental clinic.

Add your DKIM selector, or leave it empty and we try the common ones.

Then press Check email setup.

You get a score out of a hundred, from our checklist.

The tiles show where SPF, DKIM and DMARC stand.

This box lists what to fix first, with a rough time for each.

Here, there are two SPF records. There must be exactly one, or SPF fails.

This table checks your records against the sender rules.

Rules that DNS cannot show are marked Check by hand.

Open How to fix to see why it matters and the steps.

Merge them into one record, and delete the extra one.

Below, your two SPF records are merged into one, ready to copy.

Second, DMARC is at p=none: it asks receivers to do nothing with failing mail.

Move it to quarantine only once your reports show all your real mail passing.

Add it at your DNS host, then check again.

You can also email yourself a PDF of the result.

The domain you send email from, the part after the @. We read its public DNS records only: nothing is sent to your mail server or your inbox.

Leave the selector empty and we try the common ones. To find yours, open an email you sent, show the original message, and look for s= in the DKIM-Signature line.

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About the Email Deliverability Checker

Enter the domain you send email from and see whether its DNS records meet the rules Gmail, Yahoo and Outlook.com set for senders. We read MX, SPF (counting DNS lookups through every include, against the limit of 10), DKIM keys at your selector or the common ones, and DMARC, then explain each problem and give you records to copy. Only public DNS is read: nothing is sent to your mail server.

How it works

  1. Step 1

    Enter your domain, or any email address on it. Add your DKIM selector if you know it.

  2. Step 2

    We read the domain's public DNS: MX, the SPF record and every include, DKIM keys and the DMARC record.

  3. Step 3

    Fix what is flagged with the suggested records, and check again once your DNS host shows the change.

The sender rules

Since February 2024 Gmail asks every sender for SPF or DKIM, and bulk senders (close to 5,000 or more messages a day to personal Gmail accounts) for SPF, DKIM, a DMARC record of at least p=none and one-click unsubscribe. Yahoo asks for much the same. Outlook.com asks senders of 5,000 or more messages a day for SPF, DKIM and DMARC.

SPF, DKIM and DMARC in short

SPF lists the servers allowed to send as your domain, in one TXT record of at most 10 DNS lookups. DKIM signs each message with a key published at a selector, such as google._domainkey. DMARC, at _dmarc, says what to do with mail that fails and where to send reports. The current DMARC standard, RFC 9989 from May 2026, replaces RFC 7489.

What this tool cannot do

It reads DNS only, so it cannot tell whether a given message passes: that depends on the server that sent it and the From address. It cannot see your spam rate, reverse DNS or unsubscribe headers, and it finds DKIM keys only at the selectors it tries. Send yourself a message and check its headers to confirm.

Frequently asked questions

What is an SPF record and do I need one?

SPF is a TXT record at the root of your domain that lists the servers and services allowed to send email as you, for example "v=spf1 include:_spf.google.com ~all" for Google Workspace. Gmail and Yahoo ask every sender for SPF or DKIM, and bulk senders for both, so most businesses need one. A domain must have exactly one SPF record.

What does "too many DNS lookups" mean for SPF?

SPF allows at most 10 terms that need a DNS lookup: include, a, mx, ptr, exists and redirect, counting the ones inside each include. Over 10, the check ends in an error and SPF fails for every message. Remove includes for services you no longer use, or move a newsletter tool to a subdomain with its own record.

Which DMARC policy should I start with?

Start with p=none and a rua address, so you receive reports without changing how your mail is treated. p=none meets the Gmail, Yahoo and Outlook.com rules for bulk senders. When the reports show every service that sends your real mail passing, move to p=quarantine, and later to p=reject, which asks receivers to refuse mail that fails.

How do I find my DKIM selector?

Open an email you sent, show the original message or its headers, and find the DKIM-Signature line: the selector is the value after s=. Google Workspace uses "google" by default, Microsoft 365 uses selector1 and selector2, and Zoho Mail lets you name your own. Enter the selector here to check its key.

Will this stop my emails going to spam?

It fixes one common cause: missing or broken authentication. Delivery also depends on your sending reputation and on spam complaints, which DNS cannot show. Gmail asks senders to keep the spam rate shown in Postmaster Tools below 0.10% and never to reach 0.30%, so watch it there once your records are in place.

Sources and checks

Rules last checked

The Email Deliverability Checker follows these official pages:

Yahoo's and Outlook.com's rules for senders come from Yahoo's Sender Hub and Microsoft's notice for high-volume senders.

Scores, limits and suggestions marked "our checklist", "our measure" or "our suggestion" are ours, not Google's or the platform's. How our tools work

Related reading

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