This is a link to a thread about storing pastels:http://www.wetcanvas.com/forums/show...hlight=storing
hand-delivered: I just put some glassine or tracing paper over it with it taped to a backing board (cardboard since it's temporary).
mail: I would put a mat of foamcore or something to keep anything from resting on the painting. Then I sandwich between two layers of cardboard or foamcore. I use strapping tape all around the edges to fasten it together.
There's an article somewhere on WC with more ideas about storing pastel paintings. Maybe someone else will help. I think Deborah Secor may have been the writer.