Say you are an organization that regularly sends out e-newsletter updates to an email list that has been curated over the years by people signing up at events and/or through online sign-up forms. You are based in the US and most of the members of your email list are in the US, but a significant plurality are from abroad and a substantial number of those individuals reside in the EU. The GDPR is thus triggered for you (meaning you must comply).
Does this situation trigger the GDPR obligations (for example, the rights afforded to data subjects, the steps taken to protect their data, etc.) for every member of your email list regardless of where they live/reside/are or just for those individuals on your email list who are in/live in/were in EU at the time they signed up?