Email authentication is an important part of keeping your email secure and ensuring that messages from you are trusted by receiving services. One of the most powerful tools for authenticating emails is DKIM records, which can help protect your sender's reputation and reduce the chance of phishing or malicious activity on your domain.

According to recent studies, only 0.04% of 1.5 billion domains have implemented DKIM, while another report states that 79.9% of companies leave their consumer data vulnerable by not using DKIM records.

If you want to avoid losing your data in the wrong hands, this guide is for you.

In this article, we’ll discuss:

  • What does DKIM mean, and why is it important?
  • What is a DKIM record?
  • DKIM Record vs. DKIM Header: What’s the difference?
  • How DKIM Records and DKIM Headers work
  • Resources on how to set up a DKIM record

What does DKIM mean?

DKIM (Domain Keys Identified Mail) is an email authentication method designed to detect forged sender addresses in emails. It uses digital signatures based on public-key cryptography and key server technology to verify the identity of a sender domain and the message’s integrity.

When an email arrives, DKIM checks if it was sent from an authorized sender. If it was, the email is accepted; otherwise, it’s rejected or marked as suspicious. DKIM also helps protect against phishing and spamming attempts by ensuring that emails are sent from legitimate domains. If you wonder why are my emails going to spam, it is due to being processed through the DKIM authentication.

What is a DKIM record?

A DKIM record is a way to add an extra layer of email security. It works by adding a signature to outgoing emails that can be used to verify the sender’s identity. By verifying the sender's authenticity, you can help ensure that your emails are not being spoofed or sent from malicious sources. This helps to protect your emails from being flagged as spam or falling victim to phishing attempts.

Why DKIM Is Important

DKIM is important because it helps to ensure that the email sender is a legitimate entity. Spammers often use certain "spam trigger words" in their emails, such as promotions or offers. DKIM works by verifying the domain of the email sender.

Here are two major reasons why DKIM is important.

DKIM Boosts Your Sender Reputation

By verifying the email sender's domain, DKIM helps boost your sender reputation. This means that you are more likely to have emails delivered to the inbox instead of being filtered out as spam. This helps ensure that your emails are reaching their intended recipients.

While on the topic, it is also important to understand soft bounce vs. hard bounce to improve your sender reputation and deliverability.

DKIM Helps Validate Your Email Account and Prevent Spoofing

Spammers often spoof email addresses to try and get around filters. DKIM helps verify that the email is from the sender, thus helping to prevent spoofing attempts. It also helps to validate your email account and protect it from unauthorized access.

DKIM Record vs. DKIM Header: What’s the Difference?

DKIN Records

The DKIM record is a DNS record used to verify an email's legitimacy. It contains the public key that verifies the email’s digital signature.

DKIM header is part of the email itself. It contains encrypted information that verifies that the email has been signed by its sender and is not a fraud. DKIM headers are added to emails when sent on behalf of an organization or domain.

The major difference between the two is that the DKIM record is stored in the DNS (Domain Name System), while the DKIM header is included as part of the email.

DKIM Record in Action

Here is how the DKIM records work.


A DKIM signature is added to an outbound message’s header. This signature is created using the sender's domain name (or DKIM selector) and a private key. The combination of the two makes a unique and specialized name for the sender's email domain. DKIM records use the following format for names:



When the recipient's mail server receives the message, it uses DNS to look up and validate the associated DKIM record. The record must contain the same DKIM signature that was added to the message header.


The TTL is the length of time that the record remains valid. This serves as an extra layer of security, ensuring that the record cannot be reused over a prolonged period. Once the TTL has expired, the recipient's mail server will reject any messages with that DKIM signature.

DKIM Headers in Action

The DKIM protocol introduces a header attached to each email message sent from the domain in question. This header contains a cryptographic signature, which proves that the message was sent from the sender listed on the From line.

When an email recipient's server receives a message, it will check the sender's domain to see if there is a valid DKIM record. If it finds one, the server will use that public key to decrypt the header and verify that the sender's private key generated the signature. If everything matches up, it can be assumed that the message is actually from the sender and not an impersonator.

Resources on How to Set Up a DKIM Record

Here is how you can set up a DKIM record:

Google workspace guide:

Office 365 guide:

Ensure to select the recommended DKIM selector by your service provider:

  • Google/Gsuite - "google"
  • Office 365 - "microsoft"
  • Other service providers - "default"

Key Takeaways

DKIM is a powerful tool that can help protect your domain from spoofing and unauthorized access. It adds an encrypted signature to the message header, which must be validated against a DKIM record to pass through filters. To recap:

  • The name of the DKIM record should contain the sender's domain name or selector, while its content contains a public key used to verify the digital signature. Setting up these records involves creating a unique DNS entry with specific information about how long it will remain valid (TTL).
  • DKIM adds an encrypted signature to email messages sent on behalf of an organization or domain.
  • DKIM record is stored in the DNS (Domain Name System), while the DKIM header is included as part of the email.

Want unlimited email-sending accounts, warmups, and smart AI help to upscale your email outreach program? Sign up today with Instantly.