Surely they have some offices? As a small company that has no offices, I actually run into problems at times because we don't have an official office address. For example, some financial and other types of companies want things like a copy of an office lease or a utility bill in the name of the company.
Probably not an issue for a public company like Dropbox. I suspect they have an official address and SEC filings ought to demonstrate they're real as much as an office lease.
