I'd be careful about that letter. If it says if you don't respond within a short amount of time then they will consider it a valid debt and get a judgment or something against you if you do nothing. It's more hassle than it's worth by just ignoring it.
If it's well past the SOL, then just tell them that you know nothing about the "ALLEGED" debt and you are disputing any and all parts of the alleged debt. Also tell them that you are requesting a verification and they need to provide you with:
1. Validation of the alleged debt from the ORIGINAL creditor.
2. An ORIGINAL copy of the original creditor's paperwork or contract that you supposedly signed, with your original signature, with the original creditor.
3. A "statement of account" of the alleged debt DIRECTLY from the original creditor. Not one that the collection agency or their attorney has reprinted from their system of records.
4. A valid document showing your last payment or payments of the alleged debt to the original creditor AND a valid document showing if the alleged debt was "charged of" or "written off" (and when) or not by the original creditor.
5. A copy of the "associate entity" agreement between them and the original creditor showing they are giving the collection agency the power to send you a bill for an alleged debt and to even deal with you in the first place.
6. Any and All paperwork and legal proof from the original creditor that you may have forgotten to mention concerning the alleged debt from the original creditor.
IF they cannot or will not provide you with what they are supposed to when you request it then you are requesting a "cease contact" by them and their companies now and in the future about an alleged debt that you know nothing about and one that you think is a bogus collectible debt.
My mother was a collection's agent for many years. If they don't provide you with a verification from the ORIGINAL creditor showing that it is a legal, collectible debt then you can bury them in paperwork and cause many problems by going to the BBB and the state attorney general's office and you can even sue them if they do not provide proof from the original creditor and continue to "harass" you. If you ask for the right kind of verification then by law...they MUST provide it to you.
There is a time limit for when you need to get your requested verification. I believe it's 30 days.
I recently just got a letter from out of the blue also and I wrote a letter which consists of the stuff that I told you to request also. I believe that the SOL has past...but not 100% sure. But still....they must, by law, provide me with the stuff from the original creditor and if they have written it off or charged it off...then it's still an uncollectable debt.
Writing them back will stop them in their tracks and cause you possibly less hassle to worry about.
All 3 Fico scores 800+