Methods, systems, and articles of manufacture consistent with the present invention send a document with a network address to a recipient, where it is determined to send the document to the recipient, a timer value is incorporated into the network address, and the document is sent with the incorporated network address to the recipient. The light diffusion layer is a layer including a translucent resin and translucent particles having a refractive index different from a refractive index of the translucent resin. A set of seed words from the plurality of texts are labeled as being of positive sentiment or of negative sentiment with the computer system.