DKIM stands for DomainKeys Identified Mail. It is an email authentication method that enables senders to prevent email content from being altered during the delivery process.
Based on public key cryptography, DKIM works by adding a digital signature to the message header. When the recipient receives an email with DKIM, they verify the digital signature to ensure its validity. If the signature is valid, they know the message has remained unaltered during the transfer.
How Does DKIM Work?
During the DKIM authentication process, the sender’s domain generates a pair of cryptographic keys. When an email is sent, the sending server adds a DKIM signature to the message header using the private key. The sender’s domain publishes the public key in a DNS record.
Upon receiving the email, the recipient’s server retrieves the DKIM signature, queries the DNS for the public key, and verifies the signature’s integrity by comparing it to a computed hash of the email’s headers and body. If the signature is valid, the email is considered authentic and unaltered, protecting against forgery and tampering.
What is a DKIM Record?
A DKIM record is a set of machine-level instructions added to your DNS settings. It informs the internet that the messages are coming from an authenticated source, allowing mail servers to verify that a message has not been altered en route to its destination.
DKIM Signature
A DKIM signature is a cryptographic signature added to the header of an email message that verifies its authenticity and ensures it has not been tampered with during transit.
DKIM Selector
How Does DKIM Work?
During the DKIM authentication process, the sender’s domain generates a pair of cryptographic keys. When an email is sent, the sending server adds a DKIM signature to the message header using the private key. The sender’s domain publishes the public key in a DNS record.
DKIM Record Example
v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQEBA…
Why do you need DKIM?
Businesses need DKIM to authenticate their outgoing emails and ensure their legitimacy. DKIM plays a pivotal role in bypassing MITM attacks and unwarranted changes made to email content by third parties.
DKIM prevents message alterations
When you ask yourself, what is DKIM doing to prevent email fraud, get this: the digital signature is a failsafe that cannot be decrypted if the email has been intercepted and altered, so the email gets rejected
DKIM minimizes domain spoofing
An email sent by an attacker through your domain won’t have your private signature on it, and it will fail to authenticate, which is yet another insight into what is DKIM protecting your organization against.
DKIM reduces email spam
What is DKIM popularly known for is a reduction in spam emails. Configuring DKIM will greatly reduce the chances of your email ending up in the spam folder, especially with an email marketing campaign.
DKIM boosts email deliverability
Moreover, when you set up DKIM, it improves your reputation as a verified source in the eyes of customers, partners, and other services.
How Does DKIM Prevent Spoofing?
DKIM prevents email spoofing by adding a unique signature to each email, acting like a digital fingerprint. This signature verifies that the email came from the claimed sender and hasn’t been altered during transit. By confirming that the signature matches the email’s contents, DKIM ensures that emails are genuine and not forged by a malicious party pretending to be someone else.
What are the Limitations of DKIM?
While DKIM is crucial for message authentication, it has certain limitations:
- Sender Authentication: DKIM authenticates the sender’s domain name, not the individual sender. If someone has access to your email account, they can still send emails in your name, even with DKIM enabled.
- Public DNS Records: DKIM requires public DNS records for verification. Incorrectly set up public DNS records or mismatches with private DNS records, common in small businesses, can lead to DKIM failures.
- Spam and Phishing: DKIM alone does not prevent spam or phishing attempts. While it makes forgery harder for bots by requiring access to your private keys, it should be paired with DMARC for comprehensive protection.
Pairing DKIM with DMARC
Pairing DKIM with DMARC provides well-rounded protection and ensures smooth email deliverability. Using both protocols reduces the risk of being blacklisted by spam filters, improving the chances of your emails reaching their recipients.
Additionally, this combination helps protect your brand. Spammers often spoof domains they think are less likely to report them as spam, but if those domains have DKIM set up, it becomes harder for spammers to succeed. The beauty of pairing DKIM with DMARC is that they work together seamlessly to provide multiple layers of protection against spoofing attempts while giving senders options on handling their mail if something goes wrong during delivery