Unclaimed mail refers to letters and shipments that were never delivered to their intended recipient, frequently due to the recipient's incapacity to pick them up, inaccurate addresses, or unpaid postage. In the United States, unclaimed mail may be held by the postal service for a specific amount of time before being returned to the sender, auctioned off, or disposed of legally. Knowing what happens to unclaimed mail allows people to either reclaim valuable items or participate in legal auctions where such shipments are sold. Learn what mail is left unclaimed, why it happens, and how to get it back before it's too late.