Recently, use of an electronic document such as an electronic mail or e-mail is gradually increased.  Transmission of an electronic document is difficult to be recognized real time for a user who is not always connected to a network such as the Internet.  To solve the problem, the SMS has been used as a method to notify receipt of the electronic document.  However, since a huge number of spam mails are received, if the SMS is received for all mails, the user is heavily inconvenienced thereby. 
Also, whenever a mail server tries to filter such spam mails, since the spam mails pass through a fire wall by frequently changing IDs, it is a big problem to use the SMS as a mail arrival notification on a receiver's burden. 
To solve the problem, recently, mail portal service providers have suggested a method of sending the SMS on a sender's burden when there is an urgent need to notify transmission of an electronic document. 
FIG.  1 illustrates an example of a conventional method of notifying transmission of an electronic document by sending an SMS.  Referring to FIG.  1, according to the conventional notification method, after an email is transmitted, a message input window 110 and a mobile terminal input window 120 are displayed so that a sender needs to input again a content about the transmission of an email.  Since such method is inconvenient for users, the number of users using the service has not noticeably increased.  Further, according to the conventional method, there frequently occurs a case of sending an email to an incorrect email address due to an incorrect selection of an email address.