is it possible to do an email sign up popup on entry with discount code

Site URL: https://honeythemoon.com

I'm looking to do an email sign-up popup on entry. I would like to send an auto email with discount code. And, is there any way to make the discount code single use, or single use per email account? I'm guessing no, since auto generating a DC and attaching it to an email account seems like a stretch for Squarespace.

If no, are there any solutions to reward people for signing up to receive emails, but not allowing them to use the discount code every time they return for another order? Thanks in advance.

JS