1. An apparatus for measuring a mail size and acquiring mail information, the apparatus comprising: a plurality of height measurement sensor modules configured to, when a mail is placed in a weight measurement space with a reflective plate installed therein, sense position information used to measure a size of the mail by using the reflective plate; a height value generation controller configured to calculate a height value of the mail, based on the position information sensed by the plurality of height measurement sensor modules; and a mail information generator configured to extract a barcode and an address region from an image of the mail acquired by a camera, read out the barcode from the extracted barcode and address region to recognize an address, and generate mail information, wherein, the reflective plate is divided into a plurality of columns, except for an initial position value used to identify a general mail standard, position values of the plurality of columns are arranged at the same intervals and registered to be identified by the plurality of height measurement sensor modules, and the plurality of height measurement sensor modules sense position information of the plurality of columns into which the reflective plate is divided.