is an email security standard designed to ensure that messages aren’t altered in transit between the sending and recipient servers.
Email providers who validate DKIM signatures can use information about the signer as part of a program to limit spam, spoofing, and phishing, although DKIM does not tell receivers to take any specific actions. Depending on the implementation, DKIM can also ensure that the message has not been modified or tampered with in transit.
Please check this link
for more information on DKIM.