Per California Law EVERY email must have an unsubscribe method.
Your group emails do not.
As a result, I spend time every day deleting emails from you sent to
people that are no longer employed here.
groups do have an unsubscription. if the group is called "firstname.lastname@example.org" you can unsubscribe by sending a blank email to email@example.com . This will cause a confirmation-request sent to your email-addres, and if you open it and reply to it you will be unsubscribed.
"California law" doesn't mean much on a worldwide website