The address I was given last week to send in paper vouchers added another new street address line to the mailing address posted in the wiki. Hoping to get one more person to confirm, but my voucher seems to have made it to its destination even if I had to follow up with Reservations to actually get ticketed after getting a "Payment Failure" notification from AA.
American Airlines
1 Skyview Drive
M.D. 8A701
Fort Worth, TX 76155