Polyethylene terephthalate yarn is prepared by spinning under high stress conditions in the transition region between oriented-amorphous and oriented-crystalline undrawn yarns by selection of process parameters to form an undrawn yarn that is a crystalline, partially oriented yarn with a crystallinity of 3 to 15 percent and a melting point elevation of 2 to 10 C. A transmitted electronic mail is transmitted to a destination by way of the communication contents certification apparatus, and the transmitted electronic mail is stored in a communication contents storage means when it is transmitted by means of the communication contents certification apparatus. The lens assembly is triangular in shape.