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What Is DKIM? (And How to Set It Up)

This guide explains DKIM in plain English and walks you through fixing it if Warmerly says it's missing. No technical background needed.

What is DKIM?

DKIM stands for DomainKeys Identified Mail. It's a small, invisible stamp added to every email you send. That stamp proves the email really came from your domain and wasn't faked or tampered with along the way.

Think of it like a wax seal on a letter. Anyone can write a letter and sign your name at the bottom, but a wax seal with your actual stamp is much harder to fake. DKIM works the same way for email.

Why this matters for you:

  • It helps your emails avoid the spam folder. Mailbox providers like Gmail and Outlook check for DKIM. Emails without it look more suspicious and are more likely to get filtered out.
  • It protects your reputation. DKIM makes it harder for scammers to send fake emails that look like they're from your business.
  • It's required for good deliverability. If you're sending cold outreach or warming up a new mailbox, DKIM is one of the basic things every mailbox provider expects to see.

DKIM lives in your domain's DNS settings. DNS (Domain Name System) is basically your domain's address book — it's the place where you point your domain name to your website, your email provider, and other services. Your DNS is managed wherever you bought or host your domain (for example, Namecheap, GoDaddy, IONOS, or Cloudflare).

Step 1: Let Warmerly check it for you first

You don't need to do anything manually right away. The moment you connect a mailbox to Warmerly, we automatically check your domain's DNS for DKIM. We test it against a long list of the most common setups used by email providers like Google Workspace, Microsoft 365, Mailgun, SendGrid, Zoho, and many others.

If Warmerly shows a green "DKIM found" status, you're done. Nothing else to do — your domain is already set up correctly.

You only need to keep reading if Warmerly shows "DKIM not found."

Step 2: If DKIM is not found, get your DKIM record

Every email provider (Google, Microsoft, Mailgun, etc.) has its own page where it gives you a DKIM record to add. This record has two parts:

  1. A selector — a short name, like google or s1. Think of it as a label for this specific DKIM record.
  2. A value — a long string of random-looking letters and numbers. This is the actual "key" that proves emails are from you.

Here's how to find yours:

  1. Log in to your email provider's dashboard (for example, Google Workspace Admin Console, or your Mailgun/SendGrid account).
  2. Look for a setting called DKIM, DomainKeys, or Email Authentication.
  3. Generate or view the DKIM record. The provider will show you something you need to add as a TXT record — TXT just means a plain-text entry in your DNS.
  4. Copy both the selector name and the long value. You'll need to paste these into your domain's DNS settings next.

Every provider calls this something slightly different and puts it in a different place in their dashboard. If you're not sure where to look, search your provider's help center for "DKIM setup" plus your provider's name.

Step 3: Add the record at your domain's DNS host

Now go to wherever your domain's DNS is managed. This is usually the company you bought your domain from — not your email provider.

  1. Log in to your domain host's dashboard.
  2. Find the DNS or DNS Records section.
  3. Add a new TXT record using the selector and value your email provider gave you in Step 2.
  4. Save the record.

DNS changes can take anywhere from a few minutes to a few hours to go live — this is normal and just how the internet works. Don't panic if Warmerly still shows "not found" right away; check back later.

Step 4: If Warmerly still doesn't detect it, add the selector manually

Warmerly automatically checks dozens of common selector names. If your provider used one of those, Warmerly will find your new record on its own — no further action needed.

But some providers use a custom or unusual selector name that Warmerly doesn't check by default. If that happens:

  1. In Warmerly, go to Accounts.
  2. Click into the mailbox you're setting up.
  3. Go to Settings.
  4. Find the DKIM selector field and enter your selector.

The selector is just the part of the DNS record name before ._domainkey.yourdomain.com. For example, if your DNS record is named google._domainkey.yourdomain.com, your selector is simply google. Your email provider's DKIM setup page will show you this name — you just need the first part.

Step 5: Need exact click-by-click steps for your DNS host?

If you're not sure how to add a TXT record at your specific domain host, we have step-by-step guides with screenshots for the most common ones:

| DNS host | Guide | | --- | --- | | Namecheap | Set up DKIM on Namecheap | | IONOS | Set up DKIM on IONOS | | GoDaddy | Set up DKIM on GoDaddy | | Cloudflare | Set up DKIM on Cloudflare |

One more thing: SPF and DMARC

DKIM is one of three email-security records that work together. The other two are SPF (Sender Policy Framework) and DMARC (Domain-based Message Authentication, Reporting, and Conformance). In short, SPF lists which servers are allowed to send email for your domain, and DMARC tells mailbox providers what to do if an email fails these checks.

We cover both of those, with the same plain-English approach, in a separate guide: SPF and DMARC explained.