'recped' is right -- the gist of the note in Spanish (a very apologetic note from the P.O.) is that the parcel was damaged as a result of high-speed machinery, and that certain packaging cannot withstand the processing involved with such machinery. They did their best to repackage the parcel and apologize very politely for the incident.
My guess is that the envelope you used to ship these could not withstand the weight of nearly 90 pennies and likely burst open somewhere along the automated line, and who knows where the pennies ended up - probably scattered all over. With all the other stuff moving along the line, it likely wasn't possible for the postal workers to stop everything to search for all the missing coins.
It looks from the photo as if you might have shipped the coins all together inside a zip-lock bag that you put into the envelope. If you're shipping a large number of coins again, my suggestion would be to tape them flat onto a piece of cardboard (you can stick them down 2 rows deep if necessary), then sandwich another piece of cardboard on top (perhaps with a layer or two of tissue paper in between to hold everything in place). Then tape the two layers of cardboard firmly together with packing tape, and slide the whole thing inside a strong zip-lock bag that can then go into a bubble envelope.
Packing them this way may be more trouble and time to do, but I think it would be far less likely to get stuck in machinery and will get to your buyer in one piece. You can buy "removable" Scotch tape that will do the job nicely but not leave permanent sticky glue on the coins.
