DKIM, or DomainKeys Identified Mail, is an email authentication method that helps prove your emails really come from you—and haven’t been tampered with during delivery. It works by attaching a unique digital signature to each message, which receiving email servers can check against your domain’s DNS records.

In simple terms, DKIM is like sealing every email you send with a digital wax stamp. If the seal is intact, it’s trustworthy. If not, the message might be forged or altered.

Why DKIM matters for your business

If you’re sending any type of email—be it newsletters, booking confirmations, invoices, or replies from your business email—DKIM helps make sure:

• Your emails reach the inbox, not the spam folder
• Your brand identity is protected from spoofing or impersonation
• You comply with modern email standards, especially if you’re using services like Mailchimp, Google Workspace, or MailerLite

Spam filters are getting stricter, and many email providers now require DKIM to trust messages. Without it, you risk poor deliverability even if your emails are perfectly legitimate.

How DKIM works

DKIM uses a private key and public key system:

• Your email server (or provider) signs outgoing emails with a private key
• Your DNS settings include a public key, stored in a special DKIM TXT record
• Receiving mail servers use the public key to verify that the signature is valid

If everything checks out, the email is considered authentic. If not, it might be rejected or marked as suspicious.

DKIM in real-world terms

Imagine you write a letter and seal it in an envelope with a custom wax stamp that only your business uses. When it arrives, the recipient sees the stamp and knows the message is authentic and untampered.

Now apply that to email. DKIM’s digital signature says:

“This email really came from me, and nobody changed it along the way.”

When and where to use DKIM

You’ll need to set up DKIM if:

• You use email marketing platforms (Mailchimp, ConvertKit, etc.)
• You send emails from a custom domain email (e.g. hello@yourcompany.com)
• You use third-party tools to send transactional emails (like Stripe receipts, contact form confirmations, etc.)

Setting up DKIM

• Most major email services generate DKIM keys for you and provide setup instructions.
• You’ll add one or more TXT records to your domain’s DNS.
• Setup usually involves copying long strings of characters—don’t worry, you only have to do it once.

💡 Pro tip: After setup, test your DKIM record using tools like Google’s CheckMX or Mail-Tester.com.

DKIM vs. SPF vs. DMARC

These three work together:

• SPF: Who’s allowed to send emails from your domain?
• DKIM: Has this email been tampered with?
• DMARC: What should receivers do if SPF or DKIM fails?

Each adds a layer of trust to your outbound emails.

Bottom line

DKIM is a behind-the-scenes layer of security that helps protect your email reputation, improves deliverability, and keeps your messages authentic. Whether you send 10 emails a week or 10,000, DKIM is essential in today’s email landscape—and easy to set up with the right provider.