What is DKIM and Why is it Important


DKIM is a form of email encryption that is used to verify the source of an email. This blog covers all aspects of DKIM including its importance, utilities, and how one can set up DKIM.

Table of Contents

  • What is DKIM?
  • Where and why DKIM is used?
  • What is the use of DKIM?
  • How does DKIM work?
  • How to set up your own DKIM key?
  • DKIM for AMP Email approval from Email Clients
  • Is Mailmodo compatible with DKIM?
  • Conclusion

What is DKIM?

DomainKeys Identified Mail (DKIM) is an adequate email security standard incorporated to ensure messages are not modified while transitioning between the recipient and sending servers. DKIM permits organizations to take responsibility for transmitting a message, in a way that a recipient can verify. The organization can be the originating website, intermediary, etc. Their reputation is the basis for evaluating whether or not to trust the message for delivery.

Where and why DKIM is used?

When you have a DKIM signed email, it tends to be more legitimate to your recipients, and there are lesser chances for your email to reach spam or junk folders. Once a message has been signed using DKIM, a receiver uses this information regarding the signer to decide on the treatment to be meted out to the message. Messages from a signer with a good reputation will be subject to less inspection and scrutiny by the receiver's filters.

Any existing email foundation can use DKIM, and this works perfectly with DMARC and SPF to create robust security for sending emails. It's not mandatory to use DKIM to send emails but having this record attached to your DNS means ensuring security and secure authentication. Gmail makes use of DKIM to check for incoming messages.

What is the use of DKIM?

DKIM has a number of benefits which include providing a reliable emailing experience for recipients and better reputation and deliverability for the sender. As an email sender, here are the major benefits that should make DKIM a highly important part of your email infrastructure.

Protect your domain and secure your email

DKIM prevents email spoofing sent from your domain. When you use DKIM, every outgoing message will hold the DKIM signature and decrypt the message header and check whether there is any alteration. DKIM also enhances email deliverability and domain reputation.

Higher email security & improved deliverability

DKIM provides an extra layer of security to your emails. It is one of the primary email authentication methods for DMARC. DKIM signature helps to increase email security and prevent spoofing of emails. You can use the key of DKIM on every outgoing message. If you don't have your own DKIM domain key, then the mail providers will assume a default domain key(d=*gappssmtp.com) for all outgoing messages.

DKIM thus helps to build an enhanced domain reputation over time with the ISPs. Your domain develops an excellent sending reputation when you send an email and enhance the delivery practices, leading to good email deliverability.

How does DKIM work?

The DKIM uses public-key cryptography and a private key to sign email when the message leaves the sending server.

A signature header that is provided by the DKIM is added to the email for stronger encryption. For any email, the signature from DKIM is like a tamper-proof seal, which shows that it has come from the original domain and hasn't been tampered in-between. Every email sent is attached with a signature, which is specially configured from the email servers to use the DKIM.

When the recipient server receives the DKIM signed email, it utilizes the public key published to DNS to check the source message and the message body to see if there are any changes made during the transit. Once the recipient server verifies the signature with the public key, the message is passed on to the ESP and is authentic.

How to set up your own DKIM key?

To set up your own DKIM key, here's what you need to do.

  • The signee must add code in the appropriate agent, to perform signing, and they ought to modify their DNS administrative tools to allow the creation of DKIM key records.
  • A validator must add code to the appropriate agent and then feed the result into the portion of their system needing it, like a filtering engine.
  • The existence of a valid signature doesn't imply that the mail is acceptable for delivery. Acceptability requires an assessment phase. Therefore, signature validation results are fed into a vetting mechanism which is a part of the validator's filter. You can read more about the deployment of DKIM here.

DKIM for AMP Email approval from Email Clients

If you want to reap the benefits of sending out interactive AMP emails, you will have to get whitelisted with Yahoo Mail, Gmail, and Mail.ru which support AMP emails. For a successful whitelisting of your sender address, these email clients require DKIM.

Is Mailmodo compatible with DKIM?

Yes, Mailmodo is compatible with DKIM. Our email specialists team helps you understand the importance of security certifications and build your IP & Domain reputation for high email deliverability. In fact, we help our users to set up DKIM without any hassle to enable them to get whitelisted for AMP email from email clients.


Security certifications increase your sender reputation and consequently provide you with better email deliverability. Growing businesses that depend on digital presence need to have an established practice to plan and follow these guidelines.

If you are looking to create and send interactive and actionable emails that get delivered right into your user's inbox, feel free to reach out to us today.

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