Exactly. The worst regex would be: /^[a-zA-Z0-9\-_]+@[a-zA-Z0-9\-_]+\.[a-zA-Z0-9\-_]+$/ Because it would invalidates `my-email+custom-inbox@example.com`. A

Exactly. The worst regex would be: /^[a-zA-Z0-9\-_]+@[a-zA-Z0-9\-_]+\.[a-zA-Z0-9\-_]+$/ Because it would invalidates `my-email+custom-inbox@example.com`. And that's a pattern I use to automatically sort incoming mails. Many websites use such a regex :(