by reference to the accompanying drawings , the premises and outline of the embodiment of the present invention are described , followed by the descriptions of the modes for realizing the invention represented herein by embodiment examples of systems and methods in the present invention , and an investment effect expected from realizing the present invention is described additionally . in the embodiment example of the present invention taken herein , the intensive processing of two or more address - indicated postal items involves postal items in the form of enveloped letters , which are wrapped for delivery through post offices . fig1 ( a ) and ( b ) show an example of an address - indicated postal item utilized in realizing the present invention and an example of a delivery schedule of the address - indicated postal items prepared by companies which cooperated in the embodiment of the present invention respectively . as shown in fig1 ( a ), in realizing the present invention , the companies may use an envelope 1 which is one of the companies &# 39 ; respective envelopes for address - indicated postal items in the form of a sealed postal item ( sealed postal letter ) for sending bills and account statements as the address - indicated postal items to be sent to each customer of each company as is . this type of envelope 1 usually has a transparent film panel for the indication of the destination address ( name and address of the addressee ) 11 through which an address indication indicated on an enclosure ( no numeral is given in the figure ), which includes such an exceptional correspondence as an account statement , can be identified from the outside of the envelope 1 . further , in this example , there is a transparent film panel 12 for indication of the sender ( name of the company ) through which the sender can be identified from the outside of the envelope 1 . on the upper right hand corner of the envelope 1 , there may be a postage - processed indication 13 , to indicate post - payment of postage , printed in advance for depositing the item in a post office . preferably , standard code information to identify the destination address ( address of the addressee ) of each address - indicated postal item should be indicated at a visually confirmable location on the surface of the envelope 1 ( but it is not indispensable ). in this example , a bar code 14 , indicated in advance on the enclosure and which can be identified from the outside of the envelope 1 through the transparent film panel 12 for the indication of the destination address along with the corresponding address indication , is used as the carrier of the standard code information indication . this bar code 14 in particular should ideally employ a telephone number ( including both analog and isdn lines , hereinafter ) used in the subscriber telephone service of the key telephone company for example , in order to uniquely identify the address of the customer . if a constituent body of the destination address indicated on the envelope 1 is a single household , usually only a single telephone line is involved in the subscriber telephone service , and the telephone number of the household defines all the members of the family in the household simultaneously ( one of the telephone numbers assigned to the household if the household has contracted for two or more service lines ). in the case of a company , a representative telephone number can be used to define all the sections and departments in the company . in other words , standard code information is required to identify only the destination address on the envelope 1 . even if the standard code information does not help identify the respective names of customers at a particular constituent body , the customers themselves experience no difficulty in receiving the bundled address - indicated postal items in the present invention simultaneously and can get their own items by opening the wrapping . the standard code information embodied in the form of the bar code 14 is not necessarily indicated in advance on the enclosure as shown in this example . for instance , a seal or stamp ( both not shown in the figure ,) for expressing the information may be impressed directly onto the surface of the envelope 1 . in short , a necessary and sufficient condition of the standard code information is to indicate the information at a visually confirmable area of each address - indicated postal item ( preferably on the address - indicated side of each address - indicated postal item ). it is also preferable that the size of the envelope 1 as used by a plurality of companies is uniform through the respective companies in consideration of functions realized by a mail wrapping system unit discussed later . ( a detailed description is presented later .) in addition to the envelope 1 ( sealed postal item ) mentioned above , the address - indicated postal items may be home - delivery items handled by private carrier services in the form of sealed postal packages ( not shown in the figure ) which are prepared on the premise that they are to be deposited in a private carrier , in addition to postcards to be deposited in the post offices . furthermore , an exceptional correspondence which is not sealed inside any envelope , such as bills and account statements , may be accepted . now describing the exceptional correspondence , herein meaning personal data items , such as bills and account statements in more detail , these types of the correspondence in most cases carry personal information ( charges etc .) related to services provided by the companies to each customer and ideally are handled via the use of sealed envelopes as a rule . most companies today use two - piece or three - piece forms in which address indication sections and correspondence contents sections ( sections indicating respective statements ) are divided by a perforated line for easy separation of the sections . the correspondence is folded along the perforated lines between the address indication sections and correspondence contents sections before being dispatched from each company so that the correspondence contents sections are sealed to be invisible from the surface of the postal items ( address - indicated surfaces ). ( in some forms , the correspondence contents sections are folded inwards and the contents cannot be viewed even from the rear side of the postal items .) it means such exceptional correspondences can be handled in the same manner as types of address - indicated postal items in the form of sealed postal items or postal items in the form of postcards without any risk of leaking personal information to third parties provided that the respective companies handle them carefully and responsibly . referring to fig1 ( b ), the companies may , in realizing the present invention , preferably unify the respective issuing days or dispatch days of the address - indicated postal items including bills , account statements , and notifications to be wrapped together into a fixed day of any week or month ( which is friday according to the example shown in the figure ). as a matter of course , the unification should not be compulsory . however , unification of dispatch days will ease intensive processing of a huge volume of address - indicated postal items at one time to result in the advantageous reduction of the unit price required to send each address - indicated postal item , which is realized by realizing the mail wrapping system unit discussed later . fig2 is a conceptual drawing of the present invention . for the purpose of simplification , the descriptions hereafter take postal items in the form of sealed postal letters and postal items in the form of postcards as an example mode of address - indicated postal items according to the present invention , which are referred to as a “ postal item ” as a common single category . as shown in this figure , in realizing the present invention , groups of multiple postal items 2 , having respectively , the same above - mentioned standard code information group by group ( bar code 14 indicating the telephone number ) which are indicated on the address indication side of the postal items in advance , are extracted from two or more postal items 1 a , 1 b , 1 c and 1 d comprising at least the envelopes 1 that are addressed to the customers of various types of companies such as a key telephone company , cellular phone company , credit card company , or a banking organ . ( in the drawing only one group of multiple postal items 2 is shown , however , in an actual embodiment of the present invention , two or more groups thereof will be extracted .) after the step of extraction , each group of multiple postal items 2 is wrapped using a wrapping envelope 3 as a specific wrapping component made as an integrated envelope of any transparent film material . the wrapping envelope 3 is made in such manner that an address indication side of a fixed postal item 2 a placed in a topmost position of the group of multiple postal items 2 can be seen from the outside through the transparent film panel 3 a when the group thereof is wrapped . in this example , a indication of the sender 31 , which comprises the name of the company which is in charge of the facility using the wrapping method of the present invention is used in lieu of the indication of the sender ( not shown in this figure ), which prepares the fixed postal item 2 a . a postage - processed stamp impression 32 impressed by the company in charge of the facility using the wrapping method in the present invention , is used in lieu of the postage - processed indication ( not shown in this figure ) impressed for the fixed postal item 2 a . in this wrapping envelope 3 , the outer areas 3 b and 3 c , in which the indication of the sender 31 and the postage - processed stamp impression 32 are indicated are opaque in an actual embodiment of the present invention . the outer areas 3 b and 3 c are colored white for example to make the area non - transparent so that the indication of sender and the postage - processed indication of the fixed postal item 2 a cannot be visually identified from the outside . it means a truly transparent area on the surface side of the wrapping envelope 3 is limited to the area ( transparent film panel 3 a ) where the indication of the addressee indicated on the fixed postal item 2 a can be visually confirmed from the outside . on the other hand , the rear side of the wrapping envelope 3 can be either transparent or opaque . where necessary , for an envelope in which the non - transparent areas 3 b and 3 c and the rear side are separately formed , any opaque material , such as paper , can be used as an alternative to the wrapping envelope 3 . an example of the system unit of mail wrapping in the present invention is described as follows . fig3 is a functional block diagram of an embodiment example of the mail wrapping system unit in the present invention . as shown in fig3 the mail wrapping system unit 4 in the example of the present invention comprises : postal item receiving trays 41 ( a plurality of receiving trays ) for receiving a plurality of postal items 1 a - 1 f which are sorted for respective delivery areas into groups having , for example , the same postal code at respective companies such as a key telephone company , cellular phone company , credit card company , banking organ , public corporation , government office ; the postal item receiving trays 41 receiving the groups of the postal items 1 a - 1 f company by company , postal item extraction unit ( extraction means ) 42 for extracting groups of the multiple postal items 2 one after another out from the postal items 1 a - 1 f which have been received in the respective postal item receiving trays 41 provided for the respective companies by , for example , optically retrieving the standard code information ( bar code 14 ) indicated on each address indication side of the postal items 1 a - 1 f and further lumping , or assembling the groups of the multiple postal items 2 having the same standard code information ; and mail wrapping and weight sorting unit ( wrapping means and weight sorting means ) 43 for the steps of directing the groups of the multiple postal items 2 extracted by the postal item extraction unit 42 , wrapping the groups of the multiple postal items 2 as lumped via the use of the wrapping envelope 3 one after another , and sorting the wrapping envelopes 3 which wrap the groups of the multiple postal items 2 in the form of bundled postal items ( bundled address - indicated postal items ) in accordance with the weight divisions specified under a delivery fee schedule adopted by the post office one after another . though not shown in the figure , the mail wrapping and weight sorting unit 43 may be provided with an expression modifying means for modifying the postage - processed stamp impression , ( postage - processed indication ) of a single postal item ( not shown in the figure ) when the postal items having the same standard code information from the items 1 a - 1 f of two or more companies are not extracted , into a type of indication which will allow the single postal item to be handled as an isolated address - indicated postal item . an example of the method to be embodied in the mail wrapping system unit 4 constructed as mentioned above is described as follows . when the companies of various industries respectively send the postal items 1 a - 1 f addressed to their respective customers at a time , the standard code information ( bar code 14 ), to identify the destination addresses , are indicated in advance on the respective visually confirmable areas on the address indication sides of the postal items 1 a - 1 f and the postal items 1 a - 1 f are sorted into specified delivery areas . these postal items 1 a - 1 f , preprocessed as mentioned above , are collected , whether periodically or not , at a facility from the two or more companies . at this point , the postal items 1 a - 1 f which have been sorted for delivery areas should preferably be sorted further for the delivery orders . this preprocessing prepares a proper sorted condition of the postal items , without need for a further sorting step , in the final stage of the operation of the mail wrapping system unit in which the groups of the multiple postal items 2 are respectively wrapped in the wrapping envelope 3 group by group . then , the groups of the multiple postal items 2 having the same standard code information are extracted group by group from the postal items 1 a - 1 f collected from the companies by , for example , optically reading the standard code information indicated on each surface of those postal items and the groups of the multiple postal items 2 extracted as mentioned above are sorted one group after another with a front surface of the fixed postal item 2 a in the topmost position of the group directed outwards . then , the groups of multiple postal items 2 are wrapped one group after another via the use of the wrapping envelope 3 . as mentioned above , indication of the standard code information is not an indispensable condition in the example of the present invention . if the standard code information is not used , the destination addresses indicated on the postal items 1 a - 1 f may be directly read via the use of , for example , an ocr ( optical character reader ). finally , the wrapping envelopes 3 , which contain the groups of the multiple postal items 2 are each sorted in accordance with the specified weight division , one envelope after another , and the sorted wrapping envelopes 3 after all the processes mentioned above are deposited as newly formed postal items with weight divisions , with the post offices which cover the respective delivery areas identified in the preprocessing . when the address - indicated postal items having the same destination address are not extracted from the two or more postal items 1 a - 1 f collected from two or more companies in the extracting step above , an isolated address - indicated postal item of any type can be handled singly . in this case , the postal - processed indication on the isolated address - indicated postal item should be modified into a type of indication suitable for the handling of the postal item as an individual postal item . alternatively the isolated address - indicated postal item may be wrapped via the use of the wrapping envelope 3 in the same manner as with the multiple postal items 2 , as a matter of course . the following points should be noted when at least a postal item in the form of a postcard is wrapped together with other envelopes 1 . for example , when the envelope 1 is wrapped together with at least one postcard , positioning the postcard in the topmost position of the same - address - indicated postal items and wrapping them all together via the use of the wrapping envelope 3 may , due to the difference in sizes between the envelope 1 and the postcard , result in the address indication on the postcard being deviated from a position which allows the address indication to be visually confirmable through the wrapping envelope 3 . ( in consideration of this problem , it is recommended that the envelopes 1 used by different companies employ an approximately uniform size and in addition , the wrapping envelopes 3 should be of a size sufficient to accommodate the envelopes 1 .) so , when at least the postcard is included among two or more postal items wrapped by the method in the present invention , it is necessary that the postcard should be placed at any position other than the topmost position ( second or below ). if the size of the envelope 1 is unified into that of the postcard , the position of the postcard need not be specified , since the above - mentioned problem will not be caused in this condition . in addition to the above , the functions of the mail wrapping and weight sorting unit 43 may be utilized further for enclosing general correspondence , which alone cannot be accepted as an individual postal item ( not shown in the figure ) in an ordinary postal service , into all of the two or more wrapping envelopes 3 or into particular wrapping envelopes 3 which have an allowance against the upper limit value of each weight division . in this case , the general correspondence must be placed at any position other than the topmost position of all the items wrapped together so that the address indication of the same - address - indicated postal item 2 a , placed topmost in the group of two or more multiple postal items 2 , can be visually identified from the outside through the transparent film panel 3 a . following the descriptions of the examples of the system unit and method in the present invention above , the economical effect available through realizing the present invention is described additionally as follows . as shown in fig4 ( a figure showing the expense saved per company resulting from wrapping two or more postal items ), when four postal items which are accepted as special local mail ( special discount rates ) are wrapped into a single package , with the total weight of the wrapping envelope 3 being within the weight range of 75 g through 100 g , the postage of the wrapping envelope 3 will be 95 yen , which results in the postage per postal item placed therein being approximately 24 yen . as a result , the saved expense per company by realizing the present invention will amount to almost 56 yen , compared with sending the same as a standard - sized postal item ( 80 yen ) under prior art . further , as shown in fig5 ( where fig . ( a ) shows the estimated annual postage saving resulting from realizing the present invention along with the number of postal items and postage , and fig . ( b ) shows the profit of a mail wrapping company in charge of a mail wrapping facility utilizing the present invention ), the amount of saving in the postal charge resulting from sending a single wrapped postal item prepared by wrapping two postal items , which is still accepted as special local item ( special discount rates . 75 yen ), compared with the postage in sending the two postal items separately as two standard - size items ( 80 yen × 2 items = 160 yen ) will stand at more than 50 percent . part of the estimated postage saving may be invested for founding a mail wrapping company and a handling charge of 2 yen per item may be collected for the operating costs of the mail wrapping company &# 39 ; s facility , so that the mail wrapping company itself can expect a profit of approximately 10 billion yen which is far beyond the equipment investment of 5 billion yen , provided that the facility processes approximately 5 billion postal items per year . the descriptions above take postal items in the form of the sealed postal letters and the postcards together for an example mode of address - indicated postal items . however , as mentioned above , the present invention may be realized with home - delivery items handled by private carrier services in the form of the sealed postal package and the exceptional correspondences in the same manner as with the above - mentioned . in this case , when wrapping two or more exceptional correspondences without including any other postal item , the sizes of these two or more exceptional correspondences of different companies are recommended to be unified to an approximately uniform size as in the above - mentioned case of wrapping the envelope 1 . on the other hand , when mixing the exceptional correspondences with other address - indicated postal items , as in the above - mentioned case of wrapping the postal items in the form of postcards together with the envelope 1 , a contrivance or other is required to place the exceptional correspondence at any position other than the topmost position of the grouped items if the exceptional correspondence is smaller than the envelope 1 . ( when these items are all one size , the exceptional correspondence may be placed topmost .) as an alternative to the wrapping envelope 3 , a film envelope ( not shown in the figure ) whose front side at least is made entirely of transparent film material to provide a corner - to - corner transparent film panel on the front side , may be used depending on the circumstances in realizing the present invention . in this case , the indications of the sender and the postage - processed stamp impression indicated on the fixed postal item placed in the topmost position can be visually identified from the outside . such envelopes will be sufficiently practical in realizing the present invention if the positions of the above - mentioned indications of the sender and postage - processed stamp impression are conveniently covered by the indication of sender 31 and the postage - processed stamp impression 32 indicated on the wrapping envelope 3 . ( though depending on the circumstances , the indication of the sender and the postage - processed stamp impression on the fixed postal item , being made purposely visible , may be used for mailing purposes .) further , in this case , the mail wrapping and weight sorting unit 43 may be provided with a sub - expression for expressing a substitutional indication so that the destination address indicated on the single same - address - indicated postal item ( a group of same - address - indicated postal items ) will be indicated as an alternative address on the front surface of the corresponding film envelope . furthermore , the specific wrapping component may , in addition to the types mentioned above , be a net type container bag ( not shown in the figure ) which is made entirely of any net formation , a transparent band wrapper made entirely of any transparent film material , or an opaque wrapper made entirely of any opaque material such as paper or the like ( not shown in the figure , both ), or an opaque envelope which is made entirely of any opaque material such as paper or the like ( not shown in the figure ), as required . when an opaque band wrapper or envelope is used , the destination address indicated on the single same - address - indicated postal item may be indicated as a substitutional expression equivalent thereto on the front surface of the corresponding opaque band wrapper or envelope by use of the sub - expression means . ( any type of a single same - address - indicated postal item above , such as any address - indicated postal item inclusive of exceptional and general correspondences , may be accepted and as a matter of course , the address - indicated surface may also be directed inwards .) in case any other wrapping component other than the above - mentioned wrapping envelope 3 is used in realizing the present invention , the example of embodiment via the use of the wrapping envelope 3 should naturally be followed in connection with the method of enclosing at least one general correspondence , the wrapping of a single exceptional correspondence which is likely to result in an actual case , wrapping types of single address - indicated postal items , or correcting postage . in addition , it is also possible to deposit bundled address - indicated postal items with a private carrier instead of the post office . while a preferred embodiment of the invention has been described above , it is to be understood that the invention is not limited in its application to the descriptions and figures presented herein and modifications may be made without departing from the spirit and scope of the present invention which allows the advantageous effects of the invention mentioned below . as has been described above , the present invention will not only greatly reduce the expenses related to each company &# 39 ; s sending address - indicated postal items such as that mail addressed to each customer of the company , but will also alleviate the inconvenience of receiving postal items on the part of the recipients of address - indicated postal items . in addition to the above , it will enable the substantial reduction of the volume of address - indicated postal items , the number of deliveries , and indoor handling work at a post office or private carrier . furthermore , with the reduced costs for sending items in general , utilization of postal services including the delivery of direct mail will presumably be most increased .