The Email, or Electronic mail, is a method of exchanging messages ("mail") between people using electronic devices. Email operates across computer networks, which today is primarily the Internet. Some early email systems required the author and the recipient to both be online at the same time, in common with instant messaging. Today's email systems are based on a store-and-forward model. Email servers accept, forward, deliver, and store messages. Neither the users nor their computers are required to be online simultaneously; they need to connect only briefly, typically to a mail server or a webmail interface, for as long as it takes to send or receive messages. (wikipedia)
This tool was developed for programmers and testers who have the constant need to enter different email in developing forms.