What Is DKIM? The Key to Email Security and Authentication
More than 90% of cyberattacks start with a phishing email, which makes email one of the easiest ways for scammers to exploit businesses and individuals. They can fake your email address, change the content of your messages, or impersonate you to trick others. It’s a serious problem, especially for businesses and anyone sharing sensitive information.
Luckily, there’s a way to protect your emails and ensure they’re legitimate. It’s called DKIM, or DomainKeys Identified Mail.
In this article, we’ll explain what DKIM is, how it works, and why it’s such a vital tool for anyone who relies on email. By the end, you’ll understand how using DKIM can help secure your emails and protect your reputation.
What is DKIM?
DKIM, or DomainKeys Identified Mail, is a protocol that establishes your emails’ authenticity. It works by adding a unique DKIM signature to every email, which is verified using a public key stored in your domain’s DNS (Domain Name System).
This process helps email providers confirm that the message comes from you and hasn’t been altered during delivery.
To understand how DKIM works, let’s break it down into its key components: the DKIM signature and the DKIM record.
DKIM signature
DKIM signature is a unique seal on every email you send to prove it’s genuinely from you. This signature, automatically added to your email’s header, is created using encryption techniques and includes a hash of the email’s content.
When your email reaches the recipient’s inbox, their email provider uses the public key stored in your DNS to verify the signature. If the signature checks out, it confirms two things:
- Your domain sent the email (authenticity).
- The content remained unaltered during delivery (integrity).
This verification reduces the chances of your emails being flagged as spam or rejected outright.
DKIM record
The DKIM record is a small but mighty piece of information stored in your domain’s DNS settings. It acts as the foundation of DKIM by providing the public key that email providers use to validate your email signatures.
Each DKIM record includes:
- Version (v). Specifies the DKIM version.
- Key type (k). Defines the encryption type.
- Public key (p). The actual key used to verify your email signature.
The DKIM record also uses a “selector,” which helps distinguish between multiple DKIM configurations, such as when you use different email services.
How DKIM, SPF, and DMARC work together
DKIM, SPF (Sender Policy Framework), and DMARC (Domain-based Message Authentication, Reporting & Conformance) are three email authentication protocols that work together to protect email communication. Each serves a unique purpose, and when combined, they create a robust defense against email spoofing, phishing, and fraud. Here’s how they work as a team:
| Protocol | Role | How It Works | Benefits |
| DKIM | Verifies the email’s authenticity | Adds a unique digital signature to each email using a private key. The sending server creates this signature, and the email is sent to the recipient’s server. The recipient’s server verifies it with a public key in your DNS records. | Ensures emails are genuine and haven’t been tampered with. Protects against email spoofing and phishing attacks. |
| SPF | Confirms that an authorized email server sent the message | Specifies which servers are allowed to send emails on behalf of your domain. It checks the IP address of the email sender against a list in your DKIM records. | Reduces the risk of unauthorized servers sending emails from your domain. Helps prevent email impersonation. |
| DMARC | Defines policies for handling non-legitimate emails | Uses both DKIM and SPF for email authentication verification. Instructs email servers on handling messages that fail these checks (e.g., reject or quarantine). Sends reports on failed authentication attempts. | Provides reporting and guidance for handling suspicious emails. Increases email deliverability by reducing malicious spam and phishing risk. |
Why DomainKeys Identified Mail (DKIM) matters for your brand
The benefits of implementing DKIM are significant, especially if you care about email deliverability and security. Here’s what it can do for you:
Prevents email spoofing and phishing
Phishing and email spoofing are some of the most common tricks cybercriminals use to deceive people. Spoofing happens when attackers forge your email address to make their messages look like they’re from you, potentially fooling your customers.
By using DKIM, you can make sure that your emails are protected with a cryptographic signature that makes it much harder for attackers to impersonate you.
Boosts email deliverability
No one wants their carefully crafted emails to end up in spam folders. Luckily, DKIM helps with that too!
When email service providers see a valid DKIM signature, it’s like a green light telling them, “This email is legitimate.” They’re more likely to trust it and deliver it straight to the inbox.
By using DKIM, you improve your email deliverability and ensure your messages reach the people who need to see them.
Protects your brand’s reputation
Your domain is an essential part of your brand identity, and it needs to be protected.
With DKIM in place, only emails that you’ve approved and signed will appear as coming from your domain. This prevents malicious actors from misusing your name for phishing schemes or fraud.
Builds customer trust and confidence
Trust is essential in business, and email communication plays a big part in how customers perceive your brand. DKIM-authenticated emails build trust with customers. They highlight your commitment to email security.
When customers receive verified emails from your domain, they’re reassured that the message is legitimate and not part of a phishing attempt. This assurance protects them and strengthens their confidence in your brand.
How to set up DKIM for your domain
Securing your emails with DKIM is straightforward. Here’s how to do it:
- Check your email provider’s support for DKIM
Most email providers support DKIM and offer straightforward methods to set it up. Popular platforms have specific guidelines for enabling DKIM. Start by reviewing the documentation or help center for your email provider.
- Generate a DKIM Key Pair
A DKIM setup requires two keys:
- Private key: Used to sign your outgoing emails. This key is typically managed by your email provider.
- Public key: Published in your domain’s DNS as a TXT record. Email providers use this to verify the authenticity of your emails.
Your email provider will either generate these keys for you automatically or guide you through generating them yourself.
- Add the DKIM record to Your DNS
Your provider will give you a DKIM record. You’ll need to log in to your domain registrar or DNS hosting service and add this record as a TXT entry. Follow the instructions provided by your email provider to ensure it’s set up correctly.
- Enable DKIM signing
Once your DNS record is in place, return to your email provider and enable DKIM signing for your domain. This setting tells the provider to attach DKIM signatures to all outgoing emails.
You may need to wait for the DNS changes to propagate (usually within a few hours) before enabling signing.
- Test and verify DKIM
After enabling DKIM, it’s crucial to test that everything is working correctly. You can use online tools or your email provider’s built-in diagnostic features to verify that:
- Your DNS record is correctly published.
- Emails sent from your domain include valid DKIM signatures.
- Monitor and maintain
Email authentication is not a one-and-done process. Regularly monitor your DKIM setup to ensure it continues to function as intended.
Secure your emails with strong DKIM signatures
Cybercriminals are always changing their tactics, but with protocols like DKIM, you can stay one step ahead. Setting up DKIM is a smart way to enhance the security and reliability of your emails. It’s a simple step that brings major benefits: better email deliverability, a stronger brand reputation, and greater peace of mind for both you and your customers.
When you’re ready to take action, make sure you have the right tools and support. With a trusted provider like Domain.com, you’ll have everything you need to secure your domain, set up DKIM, and protect your brand. Start today and make email security a key part of your business success.
Frequently asked questions (FAQs)
DKIM isn’t a strict requirement, but it’s an essential step for ensuring your emails are trusted. Without it, your emails may be flagged as suspicious, which reduces the chances of reaching your audience’s inbox.
When an email fails DKIM, it risks being treated as spam or rejected entirely. This means your message could get lost, undermining your communication efforts and potentially damaging your email sender reputation.
While you can send emails without DKIM, doing so leaves your messages vulnerable to being marked as untrustworthy. This not only impacts email deliverability but also makes it harder to establish your brand as reliable.
According to a 2024 phishing attack report, about 1.2% of all emails sent are phishing attempts. While it may seem small, that still adds up to a lot of dangerous emails being sent every day. This highlights the need for strong email security measures like DKIM to protect your business against these threats.
