At visit of different forums, chats, social networks and other resources quite often there is desire to recognize e-mail of any given person by its login on the website. By the login it is possible to find out also the postal address if you forgot it.
You enter the last words, write "Yours faithfully, …" and click "Send". And then several times a day you open the page of the mail with hope to receive the reply to the important letter. Or you call his recipient to ask whether he read your message that sometimes happens not really and conveniently. This situation is familiar to much who should contact in the course of work with representatives of the different organizations. As to learn that the letter is read without excess efforts for itself and the partners?