What to do about an American who doesn't realize I'm trying to help him?

So, about two years ago I started receiving emails from the US HealthCare.gov website, obviously not meant for me, but rather for someone with a similar name who had entered my email address accidentally. Very oddly, the HC.gov site hadn't asked for confirmation of the address on setup! At first I ignored the mails, then I tried a few similar addresses (all bounced), then I had some time one day, so I decided to see if I could find the person on social media. It was easy enough to find him, so I sent him a message, but no response. I tried asking some of his relatives (same surname) to help, but no response. So then I noticed a contact email on the footer of one of the messages, so I thought, even though that won't help him, I'd better let them know... But... My mail just bounced 😕. The mails come from a 'no-reply' address of his chosen insurer. They have a phone number, but it's a US freephone number, so I'm not going to pay for the call from here. If I'm ever in the US again, I might ring it, but, not likely! I've looked into how to contact the insurance provider, or the HealthCare.gov site, but no joy from outside the US. Anyone think of anything I haven't tried?