Below is what they're requesting, is this OK to do? And not a security concern for us?
The reason I’m contacting you is because we currently have campaigns up and running promoting your product on various search engines but do not have conversion tracking in place. In order for us to optimize our campaigns for this product, we need you to place our tracking pixel on your thank you page. This will help us improve the ads and also guarantee more relevant traffic to your product.
As soon as I hear back from you, I'll send over the pixel tracking code that we need implemented on your thank you page. Please understand that if we cannot get this integrated for any reason, we will not be able to continue promoting your product.