If you get no response from a query, does that mean the whole management company is now off limits?

I'm torn, because I know an "unread" email means absolutely nothing to the person who does or doesn't open it. On the other hand, these companies aren't large, and people talk. If I query someone at, for example, Sugar23, and get no response, should I assume the entire company is now off-limits, it's an organization-wide "no," and never try anyone else who works there? This feels extremely limiting, because there aren't a ton of management companies out there, and the people who are successful at querying seem to have sent hundreds of emails.