You should be able to use the email performance report for this. You can pick sent date to be 2017 in the set up. You can pick all emails in the filters so it brings them all in. First activity will be close to the sent date, if not the sent date. That is about the best route to go.
By chance do you have the Advanced Analytics (Revenue Explorer) add-on? If so, I've found running an Email Analysis report to be the easiest and most flexible.