Your tenants own all rights to their data. This means, for example, that if they have registered on the Allthings platform, they can unsubscribe at any time.
In addition, if they do not want to continue receiving email notifications, there must be a way for them to unsubscribe.
In the case of non-transactional notifications, your tenants will always have the option to unsubscribe themselves, since this notification was not triggered by the tenants.