How should filter paper blood specimens from newborns be stored and mailed?

Preferably send the cards on the same day of collection; if not possible, store at 4°C after the sample has dried. Dried blood specimens must NOT be packaged in airtight, leak-proof plastic bags, as the lack of air exchange causes heat buildup and moisture accumulation which can damage the dried blood spot. High temperatures can degrade enzymes, so sample cards must be transported refrigerated. (Page 14)