Auto-Responder Email: How to send the email only when certain field has been edited?

I have a form where people are registering for specific appointment time slots. When the form is initially submitted, I have it sending autoresponder confirmation emails which include the edit submission link. I'm looking for a way to send a new confirmation email if they select a new appointment time. I know I can have the email send again every time the form is edited, but what I need is a way to ONLY send an email if the appointment time is changed. If they edit any other personal information, I don't want them to receive another email. Is this possible?

Unfortunately, this is not possible at the moment, you can only send the email auto-responder when the submission is edited, but there is not a setting that will allow to send it only when certain field is edited. 

If you want, we could escalate this thread to our second as a feature request, though do note that features may take some time to be available; however, we will make sure to let you know as soon as we receive news regarding the feature. 

Please let us know, we will be glad to escalate it.