DKIM (Domain Keys Identified Mail) is an email authentication method that helps verify that an email was not altered during transmission and that it was actually sent by the domain it claims to come from. DKIM, or DomainKeys Identified Mail, is designed to prevent email spoofing and ensure the integrity of emails. It works by attaching a digital signature to outgoing emails, which is verified by the recipient's mail server using a public key stored in the sender's DNS records. This process confirms that the email was sent from the claimed domain and hasn’t been altered during transit.
When sending an email:
The sender’s mail server adds a digital signature to the email header.
This signature is created using a private cryptographic key.
When receiving the email:
The receiving server looks up the sender’s public key in a DNS TXT record (published by the sender’s domain).
It uses that key to verify the email's signature and confirm that:
The message hasn’t been tampered with.
The sender is authorized by the domain.
This is what a DNS TXT record for DKIM might look like:
default._domainkey.example.com IN TXT "v=DKIM1; k=rsa; p=MIGfMA0GCSqGSIb3DQE..."
default is the selector (used to identify the DKIM key).
_domainkey is the required subdomain.
v=DKIM1 is the DKIM version.
k=rsa indicates the key type.
p=... is the public key used to verify the signature.
Prevents Spoofing: DKIM ensures that attackers cannot easily forge emails from your domain, as they would need the private key to create a valid signature.
Improves Deliverability: By verifying the sender’s identity, DKIM helps legitimate emails avoid being flagged as spam.
Complements Other Protocols: DKIM is often used alongside SPF (Sender Policy Framework) and DMARC (Domain-based Message Authentication, Reporting & Conformance) to provide robust email security.
It adds trust to your emails.
Helps prevent email spoofing and phishing.
Improves email deliverability—especially when combined with SPF and DMARC.
In summary, DKIM is a vital tool for enhancing email security, building trust in your domain’s communications, and ensuring that your emails reach their intended recipients reliably.