Email security is a big concern in the digital age. Every day, millions of emails are sent—and many of them are fake. Hackers often send spoofed emails pretending to be from trusted sources. That’s where DomainKeys Identified Mail (DKIM) comes in.
DKIM helps protect your domain and email content. It is an email authentication method that verifies that the email hasn’t been tampered with and that it was actually sent from the domain it claims to be from.
In this article, we will explain DKIM in simple words, its importance for email deliverability and security, and how to set it up.
What is DKIM?
DomainKeys Identified Mail (DKIM) is an email security standard designed to make sure messages aren’t altered in transit between the sending and receiving email servers. It adds a digital signature to the headers of your email.
When a mail server receives an email, it checks the DKIM signature using a public key published in the domain’s DNS records. If the signature matches, it means the content hasn’t been changed.
How DKIM Works – Simplified
- Email is sent from your server or service provider (like Gmail, Outlook, etc.).
- A private key signs certain parts of the email, including headers and body content.
- The recipient server receives the email and retrieves your DKIM public key from your DNS.
- It uses this key to verify the signature.
- If the key matches, it confirms the email content is authentic and unaltered.
Think of DKIM like sealing a letter in an envelope and signing across the flap. If the seal is broken or signature mismatched, the recipient knows something’s wrong.
Why DKIM is Important
1. Prevents Email Spoofing
DKIM makes it much harder for scammers to forge your domain name and send fake emails that look like they came from you.
2. Protects Email Content
It ensures the content of your email (subject, body, attachments) is not changed after it is sent.
3. Improves Email Deliverability
Email providers like Gmail and Outlook are more likely to deliver emails to the inbox (not spam) if DKIM is set up.
4. Works With SPF and DMARC
DKIM works best when combined with SPF (Sender Policy Framework) and DMARC (Domain-based Message Authentication, Reporting & Conformance) to provide complete email protection.
How to Set Up DKIM for Your Domain
Step 1: Generate DKIM Keys
Your email service provider (like Google Workspace, Microsoft 365, Zoho, etc.) will give you:
- Private Key (kept secret)
- Public Key (to be added to your DNS)
Step 2: Add a TXT Record to Your DNS
The public key is published as a TXT record in your domain’s DNS.
Example TXT Record:
| Host/Name | Type | Value (Public Key) |
| default._domainkey | TXT | v=DKIM1; k=rsa; p=MIGf… |
The full public key is longer and will be provided by your provider.
Step 3: Enable DKIM in Your Email Service
Login to your email service panel (like Gmail Admin Console or Microsoft 365 Admin Center) and turn on DKIM.
Popular Email Providers & DKIM
Gmail / Google Workspace
- Go to admin.google.com
- Navigate to Apps > Google Workspace > Gmail > Authenticate email
- Add the TXT record as instructed
- Enable DKIM signing
Microsoft 365 / Outlook
- Login to Microsoft Admin Center
- Go to Domains > DNS Settings
- Add DKIM CNAME or TXT records
- Turn on DKIM
Zoho Mail
- Go to Zoho Admin Console
- Navigate to Email Authentication
- Add DKIM TXT record to your DNS
How to Check if DKIM is Working
You can use tools like:
- https://www.mail-tester.com
- https://mxtoolbox.com/dkim.aspx
- Send an email to a Gmail address and check “View Original” from the menu to see DKIM results.
Common DKIM Setup Issues
| Issue | Solution |
| TXT record not found | Double-check DNS and propagation time |
| DKIM signature failed | Check if email content is being altered |
| Wrong key format | Ensure no extra spaces or line breaks |
| Using both old and new keys | Clean up legacy DKIM records |
DKIM and SEO – Does It Help?
While DKIM doesn’t directly boost SEO, it:
- Helps with email outreach and link-building campaigns
- Ensures newsletters and transactional emails reach user inboxes
- Improves domain reputation, which indirectly helps your brand
Setting up DKIM (DomainKeys Identified Mail) is an essential step toward securing your email communication. It helps verify that the content sent from your domain is legitimate and unaltered. This builds trust with your recipients and keeps your domain reputation high.
For best results, combine DKIM with SPF and DMARC to create a powerful email authentication system. Always monitor your email performance and test your configuration regularly.
