Started receiving newsletters from them to my emai...

Started receiving newsletters from them to my email address out of nowhere (I don't live in the Netherlands and have never heard of them). Not only did they have my email address, they also had my name. When i asked how they got my personal data, they wouldn't tell me, which leads me to believe that they got it in an unauthorised way. This is concerning as it could also mean that they might disclose/sell people's information elsewhere.