[dallen33]

So if a user already signed up for a newsletter, via a subscribe form on a website, does this law affect subscribers of that list?

[notatoad]

If the user has signed up explicitly for the purpose of receiving the newsletter, that's an opt-in and you're fine. if you want to use that list to send emails outside the scope of what the users initially signed up for, you're getting into grey area.

[kl4m]

There is a (3 years?) grace period where businesses with "existing relationships" can request consent to become compliant.