hi @gilly_bearman,
Welcome to ODK Forum, if you have a moment, feel free to introduce yourself here
I am assuming you would be sending "Public Link" to the respondents to fill out the Form. One approach to ensure that email address in the Form matches the respondent's email address is to prefill it. For example if your public link is https://myodk.example.com/-/single/form_id?st=the_secret then you can append &d[email]=respondent_one@gmail.com
to the URL to pre-populate the email field in the Form.
So you would send unique link to each respondent and the link would include their email address.
Thanks,
Sadiq