Products Messenger allows to the shop registered and logged-in users subscribe on the filtered products results and got emails if the new products are found by their request. Good for the shop marketing as attracts more customers after they left the shop and subscribed.
Subscribe form can be included in the seacrh form directly so applied by shortcode [woof_products_messenger].
A lot of settings which allows to the site admin select how long and how many times user will be get emails, and for how many search requests user can be subscribed.
Actual from v.2.1.7