If you are a permanent resident of Panama and receive pension payments from the US (i.e SS, RR etc) then you should know that the Proof of Life forms, that must be returned, have been mailed.
If the questionnaire is not received by October, you should contact the FBU for a blank form to avoid the benefits from being suspended.
If you do not know about the Proof of Life requirement, then read the original post which is -> http://www.chiriquichatter.net/blog/2013/05/09/proof-of-life/
For general information on the SS proof of life from the Embassy, you may refer to the following link: http://panama.usembassy.gov/ssai.html
And no, you may not use a PTY or other mail forwarding address as your SSA notification address.