This is a very good practice. I've been working on a large project that takes this approach for more than just email verification. We try to validate required

This is a very good practice. I've been working on a large project that takes this approach for more than just email verification. We try to validate required information of multiple types (emails, accounts, etc.), and provide a "Move forward without validating" option after a third unsuccessful attempt. It's made for quite a better user experience overall, reducing the frustration of users sure they're submitting correct data while "the computer" thinks it's wrong, allowing them to complete the process nonetheless.