#Gp Fax
If it looks like an envelope, it can't possible be dutiable, right? Even a
cushioned envelope. I used to order a lot of small electronics parts from the
US and request that they be sent in an envelope; they were never stopped at
Customs.
And disks do now have a special mail status. Mark it "letter on magnetic
disk", or "business documents on magnetic disk" and it will usually be left
alone. First class letters do NOT have to be written on paper.
–Jim