What is a DKIM Record?

DKIM Record

Do you want to protect the contents of the emails from your domain? Well, you have to publish a DKIM record! Read to learn more about DKIM and how it works.

DomainKeys Identified Mail, also known as DKIM, is a means of identification, such as a passport or ID card. It is attached when you send an email from your server so the receiving server can confirm with you that the Hackers did not alter the message during transmission.

Read on to see how DKIM works to ensure that no alterations were made to the content of the email before it gets to the receiver.

What is DKIM?

DKIM is an email security standard mechanism designed to ensure no changes in the email from the sender on the way to the receiver. As soon as an email is sent from the server, DKIM signs that email using a private key.

DKIM adds digital signatures within the email header; regardless if the email from forwarded to a different organization, the signature will stay the same within the email header.

It is a mechanism that signs all outbound emails from your domain with a specific key called the private key. Then a corresponding public key is published to DNS records, and the receiving server can compare the two keys to see if they match.

Furthermore, this procedure ensures that there were no alterations to the email delivered to the intended recipient. Like a seal on a medication container, DKIM will confirm with the digital signature if the email body or headers are still the same or not.

What is a DKIM Record?

The DKIM public key is a random string of characters needed to verify anything signed with the private key and is active in a DKIM record. Email servers look up the DKIM record and public key in the domain’s DNS records.

The Domain Name System’s “text” (TXT) record allows a domain administrator to input text DNS (Domain Name Service). The TXT record was first known as a location for notes that humans could read. The ability to insert specific machine-readable data into TXT entries is now available. There can be a lot of TXT entries on one domain.

How Does DKIM Work?

The DKIM public key is a random string of characters needed to verify anything signed with the private key and is in a DKIM record. Email servers look up the DKIM record and public key in the domain’s DNS records.

An email server can check the DKIM DNS record, retrieve the public key, and use the public key to validate the digital signature. All emails from a particular domain include a DKIM header, which consists of a chunk of data signed with the private key; this is called a “digital signature.”

When organizations enable DKIM for their domains, the private key is secure on Microsoft servers. Therefore, all the emails from that organization will be signed digitally using the private key.

Let’s say we have two organizations, 123.com and organization 456.com. Organization 123 added DKIM records on their public DNS.

Since 123 enabled DKIM on their domain, any email from this domain will have the digital sign by DKIM since DKIM is allowed, every outbound email that DKIM digitally signs.

Let’s say 123 sent an email to 456, which DKIM will sign digitally before sending. And when 456 receives this email, the recipient server will extract DKIM signatures from the email header and reach the public DNS.

Domain 456 will ask DNS for the public key published by domain 123. Once the recipient server has the public key, the recipient server will use the public key to validate whether the public key matches the private key or the digital sign in the email.

Once the recipient email server verifies the signatures match, DKIM will pass, and the email appears authentic. And if hackers alter the email, there will be changes in the private key which will be assessed by the recipient server, which means that DKIM will fail.

How to Create a DKIM Record?

Before creating a DKIM record, you should know the mx value for the domain you want to enable DKIM. Next is the initial domain name.

Let’s have another example.


Hostname: selector 1._domainkey Points to address or value: selector1-<domainGUID>._domainkey.<initialDomain>

Hostname: selector 2._domainkey Points to address or value: selector1-<domainGUID>._domainkey.<initialDomain>

Above is the syntax of DKIM; if you want to enable DKIM in your domain, here is what you need to do.

It would be best if you replaced the “domain GUID” with the mx value and the “initial domain” with the initial domain.

It is an example of mx value “office365concepts-com.mail.protection.outlook.com,” and the initial domain is “office365labs.onmicrosoft.com,” depending on your organization and domain name.

Once you do this, DKIM will assume you are ready to add them to your public DNS. Every email from this domain will be digitally signed by DKIM using the private key.

How To Enable DKIM In Your Domain?

You can do it in just seven easy steps!

  1. Go to your DNS website provider.
  2. Go to Website DNS management settings.
  3. Then Add two “cnames.”
  4. The next step is to enter the host as selector1 (_) underscores the domain key.
  5. Enter the changed syntax with the right domain GUID and the initial domain.
  6. Repeat the step and make one more for selector2.
  7. Save all the changes you made.

And you’re done! You have now enabled DKIM on your domain!

DKIM Example Signature and Meaning of Parts.

DKIM-Signature: – This indicated that DKIM digitally signed this email using the private key.

v=1. – This implies the version of DKIM used in that particular email.

a=rsa-sha256 or rsa-sha-1; – These are the algorithms used to sign this particular email. There are two algorithms available for signing emails. rsa-sha256 or rsa-sha-1. It depends on what DKIM had for the particular email.

d=o365techlabs.com; – This indicates the domain name that has signed the particular email.

s=selector1. – This contains the selector’s name that the recipient will use to validate the email.

h=From:Date:Subject:Message-ID:COntent-Type:MIME-Version: X-MS-Exchange-SenderADCheck; – These are the headers included within the email the moment DKIM digitally signed them.

Why is DKIM Record Important?

Without DKIM, a hacker may hijack communications and transmit a message that hackers alter to the recipient. To ensure the sender is authentic and hackers did not change the content of the email during transmission, DKIM collaborates with SPF. The combination of DKIM and SPF increases security for the email system, which is a critical online communication tool.

DKIM ensures that any other parties do not alter the email received by the recipient. Thus, the signatures or domain keys help with validating whether hackers altered an email during transmission or not.

DKIM is not a requirement, but it would be a massive help for you to get a high number of emails. So it would not just reach the rightful recipients but, most importantly, that possible intruders made no changes to the email. DKIM is not a widely embraced standard; therefore, it is not a requirement. Instead, it is an optional security mechanism. You should add a DKIM record to your DNS anytime. It is practical to authenticate mail from your domain, even when unnecessary.

DKIM enables the recipient of an email to verify whether the email was valid and sent by the sender in charge of the domain. And if no one altered the content of the email. Inbox providers like Gmail and Microsoft can block messages and stop them from being delivered to recipients if DKIM does not sign them, so this is important.

How do I check DKIM Record?

You can check/validate your DKIM record using our DKIM record Checker.
  1. First, enter ‘Google’ as the selector. For example, we’re using a generated domain key from Google Apps.
  2. Then, the DKIM record correctly configures when the DKIM Checker shows ‘This is a valid DKIM key record.’
  3. If the selector has a disability, verify with your DNS provider. See if the records are put correctly in your Domain Name Server if the selector isn’t working (DNS).
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