Find out if a Signer has opened an Email

I hear from Account Reps at my Company that DocuSign has a feature that sends them an Email if the Signer has opened the Email sent to them by DocuSign. My ESign Customer Success Representative has informed my Colleague that ESign can do the same thing. I searched the SDK and the nearest thing I can find to such a thing are the signerSessionFields. However, in the first of only 2 questions regarding Session Fields it states:

For the session fields to appear in the evidence summary, you’ll need to create a signer authentication token with the session fields and use that signer token to create a signing session. Once all documents have been signed and the package has been completed, you can download the evidence summary and view the session fields.

If you can only download the evidence summary after the Package has been Completed then this does not seem to be an answer to finding out if a Signer has opened the Email sent to them. Am I missing something or is there another way to do what my Account Reps are asking?