I got this question recently.
“A well known producer lives in my area and I know his home address. He has an interest in the local area and my script takes place here. Do you think mailing my query letter directly to his home is unprofessional?”
Yes, mailing it to his home is certainly “unprofessional.” But that doesn’t mean it won’t work. I once read about a struggling screenwriter who went around Los Angeles and threw his screenplay into the backyards of producers. He supposedly got some meetings and launched his career that way. Certainly that’s unprofessional, too. Sometimes you have to think outside the box and try things that no one else is trying. You just never know what might work.
I’m not in any way endorsing this method of promoting your screenplay or suggesting you actually do it, but if you do try it, please let me know what happens… and send me the producer’s address, too!