Yes, PDF spams are now quite a common thing.

Now in an attempt to bypass detection and add other features, the miscreants are starting to add the use of crypto to the PDF files. We are starting to see new PDF spams that were ‘encrypted’ with a (unregistered) version of pdfcrypt…

The easy way to recognize it is a big yellow square before the actual spam message…and the ‘Please Register this Version of PDFcrypt’ message…