That’s right – it happened 12 years ago! And it’s still under investigation.
And now they suggest I take steps to protect myself?

Excerpt:

I am writing to inform you that the United States Postal Service, Office of Inspector General (“OIG”) recently learned of an OIG data theft that occurred in 2005. Some personal information, including social security numbers, was contained in that data. The investigation into the theft is ongoing, so I am unfortunately not able to provide more detail at this time.

We are notifying you now because your name and social security number were included in the stolen data. Your information may be in our data because you were interviewed as a part of, or were a potential witness in, an OIG investigation. We are advising you of this incident so that you can be on alert for irregularities and take whatever protective measures that you feel are necessary.