DKIM (DomainKeys Identified Mail) is an email authentication technology that proves that the sender of the email is authorised to send emails from a given domain. The DKIM digital stamp also allows you to verify that the email has not been altered in between.
DKIM technology can be activated in the My Zone control panel, through the server management under E-mail -> DKIM / SPF / DMARC.
After activation a TXT record zone._domainkey.example.com with a public key will be added to the name server. In this case, the DKIM selector iszone, the selector lets allows publishing multiple public keys for the same domain. The private key, which is used to sign emails when they are sent, remains on the server and is not displayed. The public key allows the receiving server to check whether the sender’s address has been tampered with.
DKIM signing occurs automatically on the SMTP server at the moment the email is sent.
This is why it is important to always use the correct mail server when sending an email!
Along with DKIM it is also recommended to activate SPF and DMARC. Together, these three technologies increase the legitimacy of the emails you send and also reduce the risk of emails being marked as spam.