bug: email validation

Hello Chip,

Thanks for your feedback.

Meta Box plugin uses the jQuery validation https://jqueryvalidation.org/email-method/
to validate the email. And I see that the email without an extension is accepted
https://html.spec.whatwg.org/multipage/input.html#valid-e-mail-address

You can use the basic validation: custom attribute pattern of the field with a custom pattern to validate the email input. For example: https://imgur.com/tjW9xKI

and following the documentation https://docs.metabox.io/validation/#basic-validation