What is DKIM?
DKIM, short for domainkeys identified mail, is a way of authenticating emails to prevent spoofing.
DKIM works by allowing the receiving email server to check that an email was actually send and authorized by the domain owner.
The DKIM signature is encrypted and added to the email headers.
Implementing DKIM could improve your email deliverability, especially if used with DKIM and SPF records.