[simpss]

It's actually very dependent on the country and jurisdiction.

Some EU countries require that you offer a simple and effective option to opt-out when gathering the contact details. Depending on the content, that can be a required to be an opt-in toggle.

It's not enough to offer users a way to unsubscribe once you've already started spamming them, there should be a way to not have the first spammy newsletter/newsletter group.