I received a book today via media mail. It had a stack of coupons in the package which I know is a no no with media mail. I plan to send the following pm to give the sender a heads up on sending non-media material with her books. Does the following sound friendly, but informative? I don't want to upset her. I just want her to be aware if she routinely does this.

Thanks, Pam

Due to my toddler grandson's busy fingers, your book was actually marked as received on the 4th. I actually got it today instead. I also wanted to thank you for the coupons. I can and will definitely use some of them.

However, I did want to give you a friendly note of caution. Nothing but the PBS invoice is allowed to be mailed with the book if you use the media mail rate. Media mail packages are subject to inspection at any time during their route. If this one had gotten inspected, it would have arrived to me as COD for the parcel post rate. Which is much more than the media mail rate. I just wanted you to be aware so you don't end up getting an angry message from a requestor about having to pay to receive their book.

Thank you again for the coupons and the like-new book. I have been waiting for this one to arrive so I can start the series.
 

sounds fair and tactful to me, Pam.  But you know there are always some folks who won't take any "correction" in a mature way so be prepared if this sender turns out to be one of them and let it roll off your back.

Your message is well-stated and comes across as friendly and gentle bit of advice. I've sent a few similar messages and most of the time the recipient responds with a thank you. Hopefully you won't get a grump, but if this one is, I'd go with Jeanne's advice and just let it go.

She responded very nicely and thanked me for letting her know.

Pam