You can add a text email response validation to ensure that the users enter the correct format for the email id. In the Edit page, click on the gear icon next to the Email field > Field settings page will be displayed > click Answer > click on the configure link for the Validation option > select Text, Email and click Save.

not the format , i want to check if the email is valid ..

Neartail supports only public forms. We do not have the option to check if it is valid email.