How can I make sure only one email entry is allowed per day?

We have the unique question and unique submission options. Unique question feature is using to prevent a form from submitting duplicate submissions. Example: You can set one of your form's question (like cell number or email address) to be a unique question. This will not allow a user to use the same cell number or email address to submit your form. 

Unique submission feature is using to block multiple submissions from one system or one IP address by setting the "Check Cookies Only (Loose check)" or "Check Cookies & IP address (Strict Check)" respectively.

However, these features cannot be used for daily purposes. You can find further details on these user guides:

How to set Form Limits Based on a Unique Question

How to Set Unique Submissions on a Form

How to Limit Submissions in a Form