1. Field of the Invention
The present invention relates to an electronic mail cataloging and retrieving system which is used to catalog and retrieve many electronic mails exchanged by a wide area network, and particularly to an electronic mail retrieving system which saves time and trouble required for cataloging and retrieving and facilitates the addition and change of electronic mail classifying rules.
2. Description of the Related Art
A conventional electronic mail cataloging and retrieving system of this type which is used for cataloging and retrieving electronic mails catalogues and retrieves lots of electronic mails by utilizing a virtually set mail folder. The mail folder here is univocally given a meaning by a word or word string, and each mail folder has electronic mails conforming to a set meaning in it. Namely, electronic mails are classified by a plurality of mail folders and their meanings. And, when a mail folder is opened, electronic mails kept in it can be seen. On the other hand, when a mail folder is in a closed state, electronic mails kept in the mail folder cannot be seen.
The conventional electronic mail cataloging and retrieving system uses the above mail folders to allow free cataloging and retrieving of electronic mails sent or received by a wide area network according to a user's taste.
FIG. 39 shows one example of the screen shown by a conventional electronic mail cataloging and retrieving system. The conventional electronic mail cataloging and retrieving system will be described with reference to FIG. 39.
As shown in the drawing, a screen 2900 has a mail folder display area 2901 which shows a list of mail folders defined within the electronic mail cataloging and retrieving system and a header information display area 2902 which shows a list of header information on electronic mails. Electronic mails of which the list of header information is shown on the header information screen 2902 are those stored in an open mail folder.
The mail folder display area 2901 shows a mail folder state, namely a folder symbol for showing whether or not the mail folder is open, and a folder name for showing the meaning given to the mail folder. In FIG. 39, the folder symbol corresponding to the folder name indicates that a mail folder having a folder name "Inbox" for example is open.
The header information display area 2902 shows a sending date and time, sender, title and text in part (behind the symbol &lt;&lt; in the drawing) extracted from an electronic mail stored in the open mail folder in the form modified to an at-a-glance guide.
When another mail folder other than the open mail folder is to be opened by the electronic mail cataloging and retrieving system, the following operation and process (1) to (3) are performed.
(1) One of the mail folders on which information is shown in the mail folder display area 2901 is selected.
(2) The folder symbol of the mail folder selected by the operation (1) is changed to a "folder symbol indicating its folder is open".
(3) The header information display area 2902 shows the header information on electronic mails stored in the mail folder newly selected by the operation (1) instead of the header information on the electronic mails stored in the mail folder which has been open.
And, to classify a sent or received electronic mail, the pertinent electronic mail temporarily stored in the mail folder displayed is transferred to a desired mail folder to be appropriately classified. When the entered electronic mail is once stored into the appropriate mail folder, it is shown only when the folder in which it is classified is opened.
As described above, the conventional electronic mail cataloging and retrieving system displays in a specified display area a list of header information on the electronic mails stored in the mail folder which is open and attracting attention, and switches to a focused mail folder in order to display a list of header information on the electronic mails stored in another mail folder. Therefore, header in formation on all electronic mails stored in the electronic mail cataloging and retrieving system can not be seen at the same time. When an electronic mail stored in a mail folder different from the mail folder being displayed is wanted to see, the operation of renewing the contents to be displayed in the area for showing a list of header information on electronic mails by switching the focused mail folder is frequently repeated, taking lots of time and labor. Besides, when searching electronic mails based on a meaning which does not correspond to any meaning in the mail folders, search must be done in every folders and that causes the operation of switching folder frequently. Moreover, when reclassifying electronic mails in any mail folders based on a meaning which does not correspond to any meaning in the mail folders, same operation described above is frequently repeated in order to transfer each electronic mail in some folder to other.
And, since header information on electronic mails classified in a mail folder is displayed only when the pertinent mail folder in which they are classified is opened, if a certain electronic mail is erroneously classified into a mail folder, the conventional electronic mail cataloging and retrieving system has a disadvantage that retrieval of this electronic mail involves heavy difficulties.
In addition, the conventional electronic mail cataloging and retrieving system has following disadvantages that it takes lots of time and effort to classify electronic mails, when the conventional electronic mail cataloging and retrieving system receive or send mails, it stores at first all these mails in one particular folder generally called as Inbox. Therefore, in order to appropriately classify the electronic mails as described above, the user has to check each electronic mail to classify according to its content, taking lots of time to classify the electronic mails when there are many sent and received electronic mails. In order to remedy such a disadvantage, there have been proposed a method for automatically classifying electronic mails according to classification rule defined by the user, a method for extracting a keyword by automatically analyzing the content of each mail, a method for automatically studying classification rule and the like. Among such conventional technologies, a technology of automatically classifying electronic mails according to user defined classification rules is disclosed in Japanese Patent Laid-Open Publication (Kokai) Nos. Heisei 6-162085, Heisei 2-170642, and Heisei 4-351134. And, a technology of extracting a keyword and automatically studying a classification rule is disclosed in Japanese Patent Laid-Open Publication (Kokai) No. Showa 63-175965.
But, the above-described electronic mail classifying technologies have the following disadvantages. Specifically, according to the conventional technology for classifying electronic mails according to a classification rule defined by the user, the classification rule is entered by the user through an input device such as a keyboard. Therefore, the user has to study the forms of classification rules in advance. And, as the application range of electronic mails is expanding these years, the number of rules which have to be entered is increasing, and the rules are becoming complex. Besides, since the electronic mail classification standard of each user is frequently changed, the classification rules have to be changed every time the classification standard is changed. Therefore, the conventional method of entering the classification rules through a keyboard needs increased time and trouble to prepare or change the classification rules.
And, since the conventional technology of automatically studying the classification rules in view of the contents of electronic mails requires a dictionary with enormous amounts of words and background knowledge, it is not suitable to be used with a personal computer because its disk capacity and processing speed are limited. And, since large amounts of electronic mails is required to study the classification rules, it is difficult to immediately correspond to the user's classification standard which is changed in a short period.