A great many small businesses in Singapore still run correspondence through an owner’s home, or through the first unit they rented and have since left. It works until it does not. Bank statements sit alongside personal post. A supplier writes to an address the company vacated two years ago. Somebody’s spouse signs for a registered item and puts it somewhere sensible.
Separating the two is not tidiness for its own sake. It is what makes it possible to say, later, what the business received and when — which matters to your accountant, to an auditor, and to anyone trying to work out whether a notice was ever delivered.