"Rare Penny Black Stamp on Envelope Could Fetch Record $2.5 Million at Auction"

Sotheby's is set to auction off a Mulready envelope with a Penny Black stamp, marking the first use of a prepaid adhesive stamp on a posted envelope. The historic item, sent from London in 1840, is estimated to fetch between US$1.5 million and US$2.5 million. The stamp's usage date is significant as it predates its official release, revolutionizing mail communication by introducing prepaid postage. The auction will also feature other rare items, including Michael Jordan's championship sneakers and a unique vase, with a variety of objects valued at millions of dollars.