WooCommerce: Enable Email Notification of New Order Received with Paypal Checkout.

gistfile1.php

/**
* Do this in get_paypal_args method of class-wc-gateway-paypal.php
*/

global $woocommerce;

$mailer = $woocommerce->mailer();
$email = $mailer->emails['WC_Email_New_Order'];
$send_mail = $email->trigger( $order_id );

$paypal_args = apply_filters( 'woocommerce_paypal_args', $paypal_args, $send_mail );

return $paypal_args;