DKIM (DomainKeys Identified Mail) is an email authentication method that helps verify that an email was sent by the domain it claims to come from and that the message content has not been modified during delivery.
It works by adding a digital signature to every outgoing email. This signature is created using a private key on the sending server. The receiving mail server then checks the signature using a public key stored in your domain’s DNS records.
If the signature matches, the receiving server knows that:
• the email was sent by an authorized source
• the content of the email was not altered during transit
If the signature does not match, the message may be marked as spam or rejected.
DKIM plays a critical role in protecting your domain and improving email deliverability.
Without authentication, attackers can send emails pretending to be from your domain. DKIM helps receiving servers verify that the email actually originated from your domain.
Mailbox providers such as Gmail, Outlook, and Yahoo check DKIM when deciding whether an email should reach the inbox or the spam folder. Emails with valid DKIM signatures are more likely to be delivered successfully.
Consistent DKIM authentication helps build trust with email providers. Over time, this improves your domain’s reputation and increases inbox placement.
DKIM is one of the authentication methods required for DMARC. Without DKIM or SPF, DMARC policies cannot properly protect your domain.