replying to collectors letters

Send them a debt validation letter asking that they provide copies of the following with their reply:
1. The agreement which authorizes the creditor to collect on the alleged debt.
2. The signed agreement from the debtor conforming to pay the creditor
3. The documents regarding the payments made on this account validating the amount.

Send the letter via certified mail/return receipt requested so you will have proof that the letter was delivered and signed for. If they do not respond, which they probably won't, periodically check all three credit reports to see if any derogatory info appears, or any unauthorized inquiries from them . If anything appears, you can dispute it with the credit bureaus and will have proof that you asked for debt validation.

Keep your paperwork complete. If nothing was reported in the last 16 years, it can happen now only if the debt is valid. The collection agency has to give you written info before entering anything in your credit report. Even if they do that before, the debt info must still be given to you to make sure that their collection is legitimate. Get the debt validation done before sending a dime. Send your letters through certified mail and keep all copies in your important folder. You'll need them later when you have to prove your actions during a dispute.