I only lost chips once in the mail
A regular business envelope was sent by a friend containing 7 chips, 6 made it.
There was a little whole in the corner of the envelope.
I asked the postman, he said the sorting equipment caused this and they get coins, buttons and now chips loose ( I added the chip line ) in the equipment.

For .30 -.50 you can get these padded envelopes.
They cost a few cents more to mail, but they get there and so does the chip

neal