What is DKIM? DKIM record and signature explained

Ever received an email that looks like it's from your bank or a familiar company, but something seems off? It could be a case of email spoofing, a sneaky trick where scammers try to impersonate an entity you trust. DomainKeys Identified Mail (DKIM) is your weapon against these impostors. DKIM is like a digital signature for emails, ensuring they truly come from the supposed sender and not some shady character.

DKIM can also protect your reputation as a sender. When an email arrives claiming your company name, the receiving email platform can check your special online ID to verify the signature and expose any fakes. DKIM helps keep your domain safe from spoofing attempts and maintains the integrity of your email communication.

How is DKIM important?

In today's email landscape, DKIM is crucial for several reasons.

DKIM acts as a digital shield against email spoofing. By digitally signing your emails with DKIM, it's much harder for bad actors to forge emails that appear to come from your domain. This helps protect your users from phishing attacks, and it protects your reputation.

Nobody enjoys emails landing in spam folders, especially important ones. DKIM implementation can significantly reduce the chances of your legitimate emails getting flagged as spam. This ensures a smoother email experience for both you and your recipients, allowing for better communication and stronger customer relationships.

DKIM is effective when combined with other email authentication protocols like Sender Policy Framework (SPF) and Domain-based Message Authentication, Reporting, and Conformance (DMARC). SPF verifies the authorized mail servers allowed to send emails for your domain, while DMARC provides insights into how receiving servers handle emails supposedly from your domain (even if the emails don't have DKIM signatures). This combined approach creates a multi-layered defense against email spoofing and spam.

What is a DKIM record?

A DKIM record is a digital security measure added to your domain's DNS to combat email spoofing. It acts like a digital lock and key. The record, a modified TXT record, contains a public key. Your email service provides a private key. This private key creates a unique signature for your emails, like a tamper-proof seal. Receiving mail servers use the public key in the DKIM record to verify the signature, ensuring the email came from your domain and hasn't been spoofed by someone else.

DKIM records have a unique naming format, which includes name, type, content, and TTL. Here's an example:

Name: easy-email._domainkey.zylker.com 
Type: TXT 
Content: v=DKIM1; 
p=76E629F05F709EF665853333EEC3F5ADE69A2362BECE40658267AB2FC3CB6CBE 
TTL: 6000

The content section in the DKIM DNS record includes the public key. TXT indicates that this is a DNS TXT record. TTL stands for time to live (in seconds) and indicates how long this record can be considered valid before it needs to be refreshed.

The name is recorded in this format: [selector] ._domainkey. [domain]

Here's a breakdown of the components:

• [selector]: This is a special value assigned by your email service provider. It's included in the email header and acts as an identification tag for email servers. Email servers use this selector to find the corresponding DKIM record in your domain's DNS.
• ._domainkey.: This part remains constant for all DKIM records, acting as a standard identifier within the DNS.
• [domain]: This is your actual domain name (e.g., example.com).

Imagine you use Easy Email as your email service provider, and it assigns the selector easy-email for your DKIM record. Your DKIM record will have the name easy-email._domainkey.example.com.

What is a DKIM signature?

A DKIM signature is a digital seal of authenticity attached to emails using DKIM. Similar to a tamper-proof wax seal on a letter, it verifies that the email originated from the claimed domain. When you send a DKIM-enabled email, a unique signature is created using your domain's private key. Receiving mail servers then use the corresponding public key (stored in your domain's DKIM record) to verify the signature. A successful match confirms the email's legitimacy.

DKIM: Signing your emails for security

Here's how DKIM adds an extra layer of security to your emails, similar to a digital signature:

DKIM uses a special key system. You, the sender, keep the secret key safe on your email server, while a public key is stored in a special record within your DNS server.

When you send an email, DKIM uses your secret key to sign it electronically. This signature is like a tamper-proof seal that proves the email is genuine and originated from your domain.

When an email arrives claiming to be from your company, the receiving mail server can look up your domain's DNS records. There, it finds the public key matching the secret key used to sign the email. The server then uses this public key to verify the email's signature.

This public key is stored in a specific type of DNS record called a TXT record. TXT records are like mini-notepads within DNS, allowing you to store additional information associated with your domain. DKIM is one of the many purposes for TXT records.

Note: While older setups might use a different record type, the official standard recommends TXT records for DKIM.

What happens when DKIM isn't secure?

When DKIM isn't properly configured or implemented, it opens the door to several negative consequences, impacting both email senders and recipients.

DKIM is most effective when used in conjunction with other email authentication protocols like SPF and DMARC for a more comprehensive security approach.

Here's a breakdown of the potential issues when email isn't secured by DKIM:

For email senders:

• Without a valid DKIM signature, emails might be flagged as spam more frequently. Receiving mail servers rely on DKIM verification to assess an email's legitimacy. If the signature is missing or invalid, servers will be more likely to categorize the email as spam, even if it's legitimate. This can significantly reduce email deliverability, meaning important messages never reach their intended recipients.
• Insecure DKIM can lead to spoofing attacks where malicious actors impersonate public domain names to send phishing emails. These emails might trick recipients into revealing sensitive information or clicking harmful links, potentially damaging the impersonated brand's reputation. Since recipients might associate the negative experience with the company, it can erode trust.
• When recipients see emails claiming to be from a legitimate company ending up in spam folders, it can create confusion and frustration. This can lead to a loss of trust in the brand's email communication, potentially hindering communication efforts with customers, partners, or even employees.

For email recipients:

• Poor DKIM implementation creates a vulnerability for phishing attacks. Spoofed emails that appear to be from a legitimate company can bypass security measures, reaching recipients who might be tricked into clicking malicious links or sharing personal information. This can lead to financial losses, data breaches, or even identity theft for these victims.
• Without DKIM, it becomes harder for recipients to distinguish between legitimate emails and spoofed emails. This can lead to increased wariness and a reluctance to open emails, even important ones, potentially hindering business communication and collaboration.

Conclusion

By understanding and implementing DKIM, you can take control of your email security and ensure your legitimate messages reach the inboxes they deserve. Start using a digital risk assessment tool like Site24x7 Digital Risk Analyzer to ensure your domain's email security today.