I'm writing a cease letter to a 2nd party collection agency whose address is a postal mail box in Michigan, although the statement shows another address in Delaware. Which address should I send the cease/desist letter as I'm not sure I can certify it to a mailbox.
First of all, be very careful sending a cease and desist letter. The only option that leaves them is to sue you. If you really want to do that, I'd send it to both addresses to be safe.