Penny Blue Penny Blue The Penny Blue is frequently mistaken for a postage stamp of Britain. It is from a series of proof impressions which were made at the time Rowland Hill was looking at the new colours which were to be used for the stamps which were to replace the Penny Black and the original 1840 issue of the Two pence Blue. The decision to change the black stamp to red had already been made, and at the same time the colour of the ink used for the cancellations was to be changed from red to black. Although it had been
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