We've got a few domain wholesalers on here I think. Have you ever tried to buy domains from people who weren't actively selling their domain? Does it ever work? It's been a while but I got this today: Interestingly enough, I don't own that domain - they're just blasting emails out to a large, poorly managed list. And only offered $700, which seems outrageous!
I think the biggest issue is the research before sending. If the owner doesn’t even have the domain, there’s probably not much chance the email gets taken seriously.