Determines whether the given email exists.

For more information on this and similar theme functions, check out
the {@link Conditional Tags} article in the Theme Developer Handbook.

function email_exists( $email ) {
	$user = get_user_by( 'email', $email );
	if ( $user ) {
		$user_id = $user->ID;
	} else {
		$user_id = false;
	}

	/**
	 * Filters whether the given email exists.
	 *
	 * @since 5.6.0
	 *
	 * @param int|false $user_id The user ID associated with the email,
	 *                           or false if the email does not exist.
	 * @param string    $email   The email to check for existence.
	 */
	return apply_filters( 'email_exists', $user_id, $email );
}