You may work with a token. When you create your email, you can create an object in your database that has a unique token. This token can be part of a link you send out via mail (deeplink module).
The page itself is not directly opened with this link. The link triggers a microflow that retrieves the token object. Only if it is existing, the microflow opens the page. Once the page was visited, you can delete your token object to ensure that the user is not accessing the page a second time.