Having explored how to implement an authentication system in Next.js 14 with NextAuth.js(Auth.js) in the first part of this blog, it is crucial to take the next step to ensure the validity of user information: email validation. This process is not only an additional step in the security of our application, but an essential component to ensure that interactions between the user and the platform are legitimate and secure. In this second part, we will focus on integrating email validation by sending emails, using Resend for sending emails, and React Email to create attractive and functional email templates.