Thanks Dan for the information. Interesting is the 'International Surface Air Lift' called by the US Postal Service 'Direct Sacks of Printed Matter to One Addressee (M–bags)'
here. A direct sacks is defined as printed matter sent to a single foreign addressee at a single address, where there is an International Surface Air Lift (ISAL) M-bag.
Maximum weight of a sack: 66 pounds (including the tare weight of the sack).
Cost to the Europe - Netherlands (difficult see
here).
Netherlands comes in
price group 8. If you take ISAL M-bag Prices —
this is about the cost. So a good friend in the USA who collects your heavier books or loads of (old) magazines can ship via ISAL M-bag the whole lot in one go.
Thanks to the site of the US Mail Service and the hint of Dan about ISAL I have been able to figure this out, but it remains complex
Cheers
Kees