Was alerted to the following... at a local postal outlet... when I picked up a parcel that came back to me.
Lettermail to the US must be paper only.
Sender sent lettermail to the US... contained a small booklet.
Sender got it back... with the statement he has to forward it with a customs declaration... that is Light packet.
The problem was that the booklet was coil bound.... a metal coil
A metal detector picked it up... It came back with the statement...
Do this again and it will be a $50,000 fine...
Lettermail works for paper contents but beware sending anything with a metal content....
Light Packet with a customs declaration will work for everything that fits lettermail..... and be very specific....