I'm wondering if there are any specific regulations and laws regarding the use of customer email addresses for companies (more specifically in my case, CA-based corporations). For example, say I had a user sign-up for my app and sign-in with her email address, now known to me.
I assume I can contact the customer whenever I want until she decides to unsubscribe from the mailing list (most companies do this, so I assume it's legit).
How about sharing or selling the address with a partner firm for the purpose of generating leads? I remember seeing the "do you authorize us to share your information with our partners" question on many sites before, which leads me to believe that there might be some regulation against doing that without explicit consent. If that's true, would placing the consent in the EULA be sufficient, or does it need to be truly explicit?