Validation letter or legally known as debt validation is the method of identifying a collection agency making legitimate collections. Many CA's often contact people without having any accurate account details of the consumers. In most cases, they try to make money in an illegal way.
At this point, debt validation is the best legal way by which you can get the accurate details of the debt from the third party collector. They must give you the details about the original creditor for which they are collecting. Besides, the collection agency has to be licensed in the state and it should also be put in writing. The federal government has forced this law in order to protect people from sending money to wrong business practitioners.