How to check who filled the form (customer feedback)?

I sent form through emails and see all submissions but I do need to know who actually responded (their emails). I don’t add “specify your email” in my survey, I just need to see emails under a certain sub mission. (Like in google forms). What can I do?

If your form does not have an email field or any other contact info field, it is not possible to know who submitted the form, unless you know the users IP address.

How to Find the IP Addresses of Form Respondents

So, if you need to know who submitted the form, I can only suggest you to add an email field and ask the users to submit the form again.