Per the Fair Debt Collection Practices Act, Title VIII, S805 B, this is illegal. See link at http://www.ftc.gov/os/statutes/fdcpa/fdcpact.htm. The collection agency can only contact a third party if they are trying to find you, and then can only say who they work for if asked, and cannot tell anyone that you owe money. If they have located you, they cannot talk to anyone about your debt except for A. your lawyer if you have told them to talk to your lawyer, in which case they may not be able to talk to you any more. Or B. your spouse if you tell them they can speak to your spouse. Notice that Landlord is not on this list, nor is employer, friend, customer, etc.