Mail art archives should be kept intact. A single selected piece never fits in another collection. The only way a piece of an archive can be taken out is when it is sent to another mail artist. Sometimes the problem of archiving things is just too difficult. It absorbs too much space and energy to deal with that.
Recycling is a way of keeping the energy in the network.
An archive is just static and will collect dust. Eventually everything will end up as garbage or in a museum. The dumpjard is just another museum with different visitors. In a world of classes someone is always judging what is good or bad. In mail art all energy is equal.