In this day and age, your contact information can be accessed by others much more easily than you think. Email and phone lists for one company can be purchased and used by other parties, lawfully or not. When you sign up for things online or give out your phone number for applications and other services, that information is not guaranteed to be safe and used only by the parties to whom it was given.
This is why debt relief scams are so common. Companies access this contact information and send emails and make phone calls to people claiming to be a legitimate debt-relief company; people fall victim to these tactics because the company knows their name and may sound like it has the answer to solving debt problems quickly.