What is DKIM?
DomainKeys Identified Mail is one of the Email authentication technology to protect
Recipient and Sender against mail spoofing.
In this technology, add a digital signature on header field, verify public keys at your
DNS server with the other.
This is one of the email authentication standard method mentioned by RFC6376.
Check the Public key
The key information has been described in our application; "SETTING".
Most importance is underside grayed-out character string in "Example of BIND".
How to add
Unfortunately, we cannot on top of details.
Please Make sure to DNS hosting provider or Internal Computing team.
Example
Amazon Web Service
https://docs.aws.amazon.com/ses/latest/DeveloperGuide/send-email-authentication-dkim-easy.html
Google Cloud Platform
https://cloud.google.com/dns/records
GoDaddy
https://www.godaddy.com/help/add-dns-hosting-20165
STRATO
https://www.strato.com/faq/en_us/hosting/can-i-manage-my-own-dns-entries-at-strato/