YITH WooCommerce Coupon Email System (Premium Plugin):

Discount coupons are the best way to attract customers and are the oldest yet most powerful marketing tactics. Now when WooCommerce has a built-in Coupon system why can’t we use automatic email of coupons and surprise the customer. For example, if we target customers on their birthday or anniversary and send them a discount code that is valid for that specific day. It will be highly likely that they will purchase from your store. Also at the same time, they will wait for your email next year as well.

This kind of strategy can be applied using any rules. You can send email coupons once the customer purchases a certain amount of items from your store. A festival time coupon can be sent also. YITH WooCommerce Coupon Email System Premium will let you do this with just a few clicks. Also, you can completely customize the email to make sure that Coupon is exclusively for him only and send for some reason or occasion.

Once installed and activated, you are ready to define rules in backend and extension will follow those rules to send automatic coupon codes.