I am trying to setup my own reporting for Response Rates and am hitting some struggles. I can see if an email was sent, when it was responded, etc. Unfortunately, I am struggling to find the exact field for the date the email was sent via the AO.
I believe you have to use the AO Emails object for that information. The Created At field is the date the AO sent the email, while the Email Send Time is the time the email was successfully delivered. If the email bounced then you'll want to look at the Bounce Date field for when that happened.