The "send them a confirmation email" works well for registration, but there are legitimate use cases in which you don't want to do that.
When you just want to store the email address without acting on it (e.g., think a landing page for an app that hasn't been released), the best you can do is validate using a regex since sending them a confirmation email would provide no value to the user.
When you just want to store the email address without acting on it (e.g., think a landing page for an app that hasn't been released), the best you can do is validate using a regex since sending them a confirmation email would provide no value to the user.