A method of transmitting and receiving an electronic mail includes the steps of: transmitting the electronic mail from a sender terminal to a receiver terminal, and receiving the electronic mail at the receiver terminal. The transmitting step includes the steps of producing the electronic mail including character codes of characters constituting a mail document, at least one conversion program for converting the characters to be displayed in a dynamic manner and an address of the receiver terminal, and transmitting the electronic mail. The receiving step includes: receiving the electronic mail; from a font storage unit storing character patterns corresponding to character codes, reading out the character patterns corresponding to the character codes included in the electronic mail; spreading the read-out character patterns on a bit map memory to produce bit map fonts; converting the bit map fonts by using the received conversion program according to the passage of time; and displaying the converted bit map fonts on a display device.