H & R Block Privacy Snafu

Apparently, H & R Block recently had a problem protecting prospective customers' privacy.

From KansasCity.com:

As part of a promotional campaign, the Kansas City-based tax preparation giant sent complimentary copies of its TaxCut tax preparation software to an undisclosed number of people around the country. Owing to a mail production mix-up, the mailing labels on some of the recipients' packages included their Social Security numbers.

It is unlikely that anyone but the recipients noticed. The nine-digit number was embedded in a 47-character source code. Nonetheless, out of an abundance of caution, Block recently sent letters notifying recipients of the glitch.

In the letters to the "undisclosed number" of recipients, H & R Block was quite apologetic for its breach of confidentiality. Of course, it's presumed that H & R Block had all the Social Security numbers in its existing customer data bank. They surely wouldn't have the SSNs of people who have never done business with them. Right?