Scientific Letter is an email program, designed to exchange scientific mail messages with complex equations. If the recipient is also using Scientific Letter, he will see the message text with equations included in it as graphical part, otherwise it will be displayed in LaTeX notation. The equation characters are inserted by holding down keyboard keys, which trigger a popup menu that shows additional key combination, that will trigger the special character when they are pressed. It can be a little confusing, but once you do it a few times, it is fairly easy. The email program itself is bare bones, and only designed to receive messages that were sent from other Scientific Letter users. The program supports Greek Alphabet and more than 100 symbols and equation characters.