Two penny blue Two penny blue The Two Penny Blue or The Two Pence Blue was the world's second official postage stamp, produced in the United Kingdom of Great Britain and Ireland and issued after the Penny Black. Initial printing took place from 1 May 1840, and in all 6,460,000 were printed from two plates until 29 August. Officially the stamps were valid for postage from 6 May but were only available from 8 May. It was first sold to the public at the London Inland revenue office on 6 May 1840. Except for its denomination, the design is exactly the same as
Penny Black (research project) Penny Black (research project) The Penny Black Project is a Microsoft Research project that tries to find effective and practical ways of fighting spam. Because identifying spams consumes a recipient's time, the idea is to make the sender of emails "pay" a certain amount for sending them. The currency or the mode of payment could be CPU cycles, Turing tests or memory cycles. Such a payment would limit spammers' ability to send out large quantities of emails quickly. The project's name is derived from the Penny Black, the world's first adhesive stamp used for paid postage. The goal of the