I've read here and on other threads, where swappers have used old calendars to wrap and mail their books.  I would like to try this because I have an old calendar that would be perfect to wrap around some of the mass paperbacks that I have.  However, I don't want to get into trouble with the USPS for using the pages if its not appropriate.  Has anyone ever successfully used old calendars as packing materials?

I have used old maps, calenders and wrapping paper.  The PO has never cared as long as it's been well wrapped and taped.

As you've noticed Becky, members often post their preference for using calendar pages.  I don't recall anyone mentioning problems with these pages.  I've only used them for internal padding, but have received several books with an external calendar wrapper.  With the recommended packing tape, they seem to travel just fine (probably better than brown paper that can sometimes be brittle and much better than gift wrap).