Notes automatically sent to costumer

Hi,
after installing the Woo Custom Gateway plugin, we created a couple of costum Payment Methods, and making trial purchases we noticed that, in addition to the email with the order summary, the customer also receives the email “A note has been added to your order”.
On the admin side, opening the order from the order list, an empty note is added in order notes at the same time as the order is received.
How can this be solved?
Thanks