I know this thread is 7 years old, but I just received this one today 8/25/17. Highly deceptive and I thought the Postal Service had enacted regulations prohibiting Junk Mailers from using Official Looking packaging and appearance of Government correspondence. In this case SSI. Although it is carefully worded.
I have a excellent suggestion to those receiving this garbage. If it is a postage paid envelope or in this case a postage paid Post Card, upon which they want you to write personal information, the easiest way to let them know your displeasure is to simply write no thanks in large letters across the item, and drop it in a mail box. They will have to pay for the return postage. Get a few million irate people doing that and they will get the message.
By, the way the Pennsylvannia Ave address in DC is another scam. It is a rented mail box in a UPS store, and the mail is forwarded to their true company address in Texas.