This practice is very common. I'm not saying I agree with it but you should expect that every service you signup with to do this. As the company retargeting you

This practice is very common. I'm not saying I agree with it but you should expect that every service you signup with to do this. As the company retargeting you do not know anything extra about your customers. The retargeting audience is a black box. It's Facebook you have to worry about. My suggestion is to have a different email for Facebook than everything else.