I have probably sent well over 100 books via Media Mail at the Post Office.  But yesterday, for the first time, the clerk asked me if there were any "hand-written messages or cards" in the package.  I thought that was rather odd.  I said, "No, just a book".   But it left me wondering what was going on.

Is there some new regulation that I somehow missed?  You can't now send a book Media Mail if it has a card with it??

Anyone know?  Thanks.

You can also include something that is considered to be an invoice. (The 2nd sheet of the PBS wrapper normally would qualify as this).

You can't include personal notes or letters, except the very short notes given as examples above.

Thank you!! 

I knew that members of PBS would have an answer!  

I just write any msg on the PBS notice so there is no question about the note being a letter which is first class mail.

You CAN include a note or letter, but MUST pay for a "First Class Enclosure".  That's an additional 44 cents for the first ounce, 20 cents for each additional ounce.  For offices that have a POS machine, there is a button for "First Class Enclosure" on the same screen as the DC and Insurance buttons.  It will ask the clerk for the weight of the enclosure, so be prepared to either open the package (to enable the clerk to weigh the enclosure) or be able to convince the clerk it is just 1 ounce additional, etc.