what do you actually propose that a valid email address is
To me, valid means it's an email address in control of a human who entered it in earnest. You could layer on bot defense (via recaptcha, etc) either on the email form itself or on the confirmation page linked to in the email. But in my opinion, that's a separate concern.
You're best off using a well tested browser implementation or just keeping the input loosely validated.
I'm all for using <input type=email> and letting browsers do their thing. But that's more for UX than it is for me as the site owner.
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To me, valid means it's an email address in control of a human who entered it in earnest. You could layer on bot defense (via recaptcha, etc) either on the email form itself or on the confirmation page linked to in the email. But in my opinion, that's a separate concern.
I'm all for using
<input type=email>and letting browsers do their thing. But that's more for UX than it is for me as the site owner.