Anytime you do internet biz with anyone, utilize your email account to create sub accounts. Then, if you start getting 3rd party emails of any type to that sub account, you know where it came from. Then just delete that sub account. Your main account remains unknown to them, and you get no third party trash.
When you do biz with them again sign up with another new sub account and so on. Once your biz is complete, delete that sub account, and so on.
Russellc