Automated mailing list subscriptions

We’re encountering an interesting issue with our marketplace, and I wanted to share it in case anyone else has experienced something similar. We’ve noticed that when users purchase items from a specific brand, they are automatically subscribed to a mailing list without any visible consent. It seems that the brands can control this themselves, and if they grant access to customer data to the marketplace, the same control is possible. As one might expect, most brands would not be comfortable providing all customer data to a marketplace. It appears that this is something the marketplace’s sales channel app should be able to control, as it doesn’t seem appropriate for brands to automatically market to users without consent. Am I missing something here? It would be great if this could be managed through a simple setting. Any help is greatly appreciated.

See the proposed mockup attached.