apply_filters( 'user_registration_email', string $user_email )

3462	 * Filters the email address of a user being registered.3463	 *3464	 * @since 2.1.03465	 *3466	 * @param string $user_email The email address of the new user.3467	 */3468	$user_email = apply_filters( 'user_registration_email', $user_email );3469 3470	// Check the username.3471	if ( '' === $sanitized_user_login ) {3472		$errors->add( 'empty_username', __( '<strong>Error:</strong> Please enter a username.' ) );3473	} elseif ( ! validate_username( $user_login ) ) {3474		$errors->add( 'invalid_username', __( '<strong>Error:</strong> This username is invalid because it uses illegal characters. Please enter a valid username.' ) );