I was exploring about DKIM. I read an email which was sent via sendgrid and with application from remote server. My question is , how can assign the DKIM key of own server if sender id do not exist in your mail server. I generally use opendkim. When I tried sending email from application, SPF was passed, DKIM was not there in email Header . In mail log, it shows "No signing table email@example.com"
I would like to setup this kind of mechanism. Can anyone guide me ?