With Google and Yahoo's email sender requirements coming up, I would like to set up and use Google’s Postmaster Tools: https://postmaster.google.com/managedomains
When setting this up, I’m confused which domain to enter for this question: “What domain do you use to authenticate your email?”
Should I use “www.mywebsite.com” or should it be my sending domain (that can be found in Klaviyo) “send.mywebsite.com”?