When sending material or pictures in the mail Dont put in an ordinary thin large or small envelope. I would put in a box. Mark each piece with a return label. In the box put them in a plastic bag with return address on it. I worked for the postoffice and it is not the fact that no one cares about the mail. It is the fact that most everthing is automated and if it is thin enough it will go through a machine. There are millions of pieces that go to a main post office after you put in in the mail box. The people that work for the post office do their best to catch thicker mail but sometimes some get missed. I have seen family pictures put in ordinary envelopes that are just licked and closed. The dry air pops the envelopes open and out comes every thing. Tape , tape ,everything shut. The paper sucks the moisture right out of the air at the main post offices. Sorry about your material. But hopefully this advise helps others from not losing their valued material.