Celebrities, even relatively accessible ones like Michael Douglas, receive a massive amount of mail and communications. It's simply not feasible for them to respond to everyone personally.
Here are some alternatives to consider:
* Fan mail: You can still write to Michael Douglas at his agent's address or his production company, but don't expect a personal response. However, your letter may be read by someone in his team.
* Social media: If you have a social media account, you can try reaching out to him through his official channels. However, remember he likely has a large following and it's highly unlikely he will see your message or reply.
* Attending events: If you're lucky, you might be able to meet Michael Douglas at an event or signing.
Ultimately, it's important to be realistic about the chances of receiving a personal response from a celebrity. However, you can still express your appreciation for his work through fan mail or social media.