Hi Darshan,
You need to set mail parameters in .env file for mail functionality.
MAIL_DRIVER=
MAIL_HOST=
MAIL_PORT=
MAIL_USERNAME=
MAIL_PASSWORD=
MAIL_ENCRYPTION=
SHOP_MAIL_FROM=
ADMIN_MAIL_TO=
When order successfully created then we fire this event with order data like -
Event::fire('checkout.order.save.after', $order);
and listening this event in Webkul\Admin\Listeners\Order@sendNewOrderMail
and calling a function ' sendNewOrderMail ' to send mail of order placed.
Thanks