It would be helpful if D365 Marketing offered list-unsubscribe as an option or even better if it was added by default.

What is List-unsubscribe?

List-unsubscribe is an optional email header supported by popular inbox providers like iOS Mail, Gmail, and Outlook.com. Supported inbox providers look for this header in emails and display a native unsubscribe option to users, allowing for a simple and consistent unsubscribe action.

While it can feel counterintuitive to make it easy for subscribers to stop receiving your emails, unsubscribes are actually a good thing when they serve as an alternative to a spam complaint. Our research has shown that 50% of consumers have marked an email as spam because they couldn’t easily figure out how to unsubscribe.

More info here https://help.litmus.com/article/282-what-is-list-unsubscribe