HTML5 Email Validation

Question

"With HTML5, we no longer require JavaScript or a server-side code to validate if the user's input is a legitimate email or URL address," is a common statement.

Once a user enters, how can I verify their email? Also how to display a notice without using JS if a user enters their email address incorrectly.

<input type="email" pattern="[^ @]*@[^ @]*" placeholder="Enter your email">
<input type="submit" value="Submit">