File sharing system

Abstract

To significantly reduce the work burden when a mail recipient requests re-uploading of a file deleted from a file server 30.SOLUTION: When a download request for an attached file deleted due to expiration is made from communication terminals 20, 40 used by a mail recipient, a file server 30 inquires the mail recipient who has made the download request about whether or not a request for re-uploading is necessary, and in response to a request for re-uploading from the mail recipient, the file server 30 instructs a relay device 10 to request re-uploading, and in response to this instruction, the relay device 10 transmits a request mail for re-uploading to a mail sender.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a file sharing technology that allows users to share files by separating files attached to emails on an email transmission path and automatically saving the files on a file server. [Background technology]

[0002] Conventionally, as a technology for sharing files between users, for example, Patent Document 1 proposes a file sharing technology in which a file attached to an email is separated from the email by a communication device on the email transmission path and automatically saved on a file server on a communication network, thereby sharing the file.

[0003] This file sharing technology provides higher security when sending and receiving emails and reduces the communication load required for sending emails, compared to attaching files to emails and sending them directly to the recipient. Furthermore, because this file sharing technology allows a file sharing source user to simply attach a file they want to share to an email and send it, it significantly reduces the workload of the file sharing source user when sending a shared file, compared to when the file sharing source user uploads the file they want to share to a file server in advance, separately from the email. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-175253 Summary of the Invention [Problem to be solved by the invention]

[0005] In order to make effective use of file storage resources, typical file servers set a download expiration date for stored files and forcibly delete files that have expired. As a result, if a recipient wants to share a file that has expired and been deleted again, the recipient must call or email the sender to request that the desired file be resent, which is a cumbersome process for the recipient.

[0006] The present invention aims to solve these problems and provide a file sharing technology that can significantly reduce the workload that arises when an email recipient requests the re-uploading of a file that has been deleted from a file server. [Means for solving the problem]

[0007] In order to achieve the above object, a file sharing system according to the present invention includes a relay device connected to a communication network and configured to relay communication terminals connected thereunder via a LAN to said communication network, and a file server connected to said communication network and configured to check the expiration date of each uploaded file and delete files whose expiration date has expired, wherein said relay device is configured to receive a mail transmission request for an email with an attachment sent from a sending terminal used by an email sender among said communication terminals to a mail server on said communication network, to separate the attachment from the email with attachment included in said mail transmission request and upload it to said file server, and to transmit a mail transmission request for the separated email from which the attachment has been separated to said mail server, and wherein said file server is configured to check a specified attachment file in response to a download request from a receiving terminal used by a recipient of the separated email, and download the specified attachment file; if the attachment file has expired and been deleted, the file server is configured to inquire of the receiving terminal whether a request for re-uploading of the attachment file is necessary, and in response to a response from the receiving terminal that a request is necessary, to notify the relay device of a re-upload instruction including attachment information indicating the content of the re-upload request; and in response to the re-upload instruction from the file server, the relay device is configured to send an email transmission request to the email server, requesting the email sender of the specified attachment file to re-upload based on the attachment information included in the re-upload instruction.

[0008] In addition, one configuration example of the file sharing system according to the present invention is configured such that, when the received email transmission request is an email transmission request in response to the re-upload instruction, the relay device separates the attachment from the email with the attachment included in the email transmission request and uploads it to the file server, and then transmits an email transmission request for the separated email to the email server, with only the person who requested the re-upload of the attachment as the destination, based on the attachment information included in the re-upload instruction.

[0009] In addition, in one configuration example of the file sharing system according to the present invention, when the imported email transmission request is an email transmission request in response to the re-upload instruction, the relay device is configured to separate the attachment from the email with the attachment included in the email transmission request and upload it to the file server, and to send an email transmission request for the separated email to the email server, with the destination being those who have not yet downloaded the attachment, based on the attachment information included in the re-upload instruction.

[0010] In addition, in one configuration example of the file sharing system according to the present invention, the relay device is configured to store each of the captured email transmission requests in a memory circuit, and in response to a re-upload instruction from the file server, retrieve a corresponding email transmission request from the memory circuit based on the attachment file information included in the re-upload instruction, change the destination of the email included in the email transmission request to only the source of the re-upload request for the attachment file specified in the attachment file information, and send an email transmission request for the changed email with the attached file attached to the email server. [Effects of the Invention]

[0011] According to the present invention, when a mail recipient requests the mail sender to re-upload a file that has been deleted from a file server, the request can be made with an extremely small workload. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a block diagram showing the configuration of a file sharing system according to the first embodiment. [Figure 2] FIG. 2 is an explanatory diagram showing an example of the configuration of access information. [Figure 3] FIG. 3 is an explanatory diagram showing an example of the structure of the attachment information. [Figure 4] FIG. 4 is an explanatory diagram showing an example of a message screen notifying the expiration of the validity period. [Figure 5] FIG. 5 is a sequence diagram illustrating the operation of the file sharing system according to the first embodiment. [Figure 6] FIG. 6 is a sequence diagram showing the continuation of the operation of the file sharing system according to the first embodiment. [Figure 7] FIG. 7 is a sequence diagram showing the continuation of the operation of the file sharing system according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Next, an embodiment of the present invention will be described with reference to the drawings.

[0014] [First embodiment] First, a file sharing system 1 according to a first embodiment of the present invention will be described with reference to the block diagram of FIG.

[0015] This file sharing system 1 is configured to separate attachments from emails sent from communication terminals 20 (A, B, ...) connected to a LAN (Local Area Network) and automatically store them on a file server 30 connected to a communication network NW such as a WAN (Wide Area Network) typified by the Internet, thereby enabling attachments to be shared between sending and receiving users exchanging emails via a mail server 31 on the communication network NW.

[0016] The file sharing system 1 includes a relay device 10 and a file server 30 as main devices.

[0017] The relay device 10 is connected to a communication network NW and configured to relay and connect a communication terminal 20 connected thereunder via a LAN to the communication network NW.

[0018] The file server 30 is generally a general file server that provides file sharing services, is connected to the communication network NW, and is configured to store uploaded files until their expiration date, forcibly delete files whose expiration date has passed, and, in response to a download request from the communication terminal 20 or a communication terminal 40 outside the LAN, return the requested file after successful authentication.

[0019] [Principle of the present invention] As mentioned above, in file sharing technology in which email attachments are uploaded to file server 30 and shared, in order to ensure resources for storing files, in many cases file server 30 assigns an expiration date (validity period) indicating the period during which the file can be downloaded when it is saved, and deletes the file when the expiration date expires. However, with this type of configuration, if an email recipient wants to share a file that has expired and been deleted, they must call or email the email sender to request that the desired file be resent, which is a cumbersome process for the email recipient.

[0020] In many cases, the file server 30 manages, for each uploaded attachment, link information indicating the storage destination of the attachment and the expiration date of the attachment. The communication terminals 20 and 40 used by the email recipients are configured to access the file server 30 from a browser and, after successful authentication, download the desired attachment. When the attachment is downloaded, various messages can be exchanged between the file server 30 and the communication terminals 20 and 40. The relay device 10 can also generate emails with any content and send them to the communication terminals 20 and 40 via the email server 31.

[0021] The present invention focuses on the various configurations provided in the file server 30, communication terminals 20, 40, and relay device 10, and is configured so that when a download request is made from the receiving terminal used by the email recipient for an attachment that was deleted due to expiration, the file server 30 inquires of the receiving terminal as to whether or not a request to re-upload the attachment is necessary, and in response to the request for re-upload from the receiving terminal, the file server 30 instructs the relay device 10 to request a re-upload, and in response to this instruction, the relay device 10 sends an email requesting a re-upload to the email sender.

[0022] As a result, a request to re-upload an attachment that was deleted due to its expiration date is automatically notified to the email sender from file server 30 and relay device 10. Therefore, when an email recipient requests re-uploading of a deleted attachment, the email recipient only needs to request re-uploading from file server 30. This eliminates the need for the email recipient to perform the cumbersome task of requesting the email sender to resend the desired attachment by phone or email, as in the past, and makes it possible to request re-uploading from the email sender with an extremely small workload.

[0023] [Configuration of the first embodiment] Next, the configuration of the file sharing system 1 according to the first embodiment will be described in detail with reference to the block diagram of FIG.

[0024] [Repeater] The relay device 10 is composed of a server device as a whole, and includes a communication I / F 11, a UTM processing circuit 12, a memory circuit 13, and a control circuit 14 as main circuit sections.

[0025] [Communication I / F] The communication I / F 11 is connected to the communication network NW via a communication line L1, and is configured to relay and connect the communication terminal 20 connected thereunder via a LAN to the communication network NW. The communication I / F 11 is also configured to take in various messages exchanged between the communication terminal 20 and the mail server 31 when sending and receiving emails, and output them to the control circuit 14, and to relay and transfer various messages exchanged between the control circuit 14 and the file server 30 and the mail server 31 via the communication network NW.

[0026] [UTM processing circuit] The UTM processing circuit 12 comprises a security check circuit that performs multiple security checks to guard against threats such as computer viruses and unauthorized access, and is configured to perform security checks on attached files separated from emails.

[0027] [Memory circuit] The memory circuit 13 is made up of memory circuits such as semiconductor memory and a hard disk, and is configured to store processing data and programs for the control circuit 14 to perform file sharing processing using the file server 30. The programs are read from an external device or a recording medium (neither of which are shown) and stored in the memory circuit 13 in advance.

[0028] [Control circuit] The control circuit 14 is composed of a computer having a CPU and its peripheral circuits as a whole, and is configured to read a program stored in the memory circuit 13 and operate in cooperation with the CPU to perform attachment file sharing processing in cooperation with the file server 30.

[0029] Specifically, the control circuit 14 is configured to receive, via the communication I / F 11, a request to send an email with an attachment sent from a sending terminal among the communication terminals 20 used by the email sender to a mail server 31 on the communication network NW, separate the attachment from the email with the attachment included in the request to send an email, upload it to the file server 30 via the communication I / F 11 and the communication network NW, generate a request to send an email with the attachment separated, and send it to the mail server 31 via the communication I / F 11 and the communication network NW.

[0030] Furthermore, when generating the separated email, the control circuit 14 is configured to add, to the body of the separated email, access information required to download the attached file, which is notified by the file server 30. As shown in Fig. 2, the access information includes link information (URL) for the email recipient to access the file server 30 and download the attached file, an expiration date indicating the period during which the attached file can be downloaded from the file server 30, and information such as a password for authenticating that the recipient is the email recipient of the separated email to which the attached file was attached.

[0031] In addition, the control circuit 14 is configured to generate an email sending request for a request email requesting the email sender of the specified attachment to re-upload the file, based on the attachment information included in the re-upload instruction, in response to a re-upload instruction from the file server 30 notified via the communication network NW and the communication I / F 11, and to send the request email to the email server 31 via the communication I / F 11 and the communication network NW.

[0032] As shown in Figure 3, the attachment information includes information for identifying the attachment, such as link information (URL) for downloading the attachment and the storage date and time indicating the date and time when the attachment was uploaded to the file server 30.

[0033] [File Server] The file server 30 is configured to check the specified attachment in response to a download request from the receiving terminal used by the recipient of the separated email sent from the relay device 10, and if the attachment has expired and been deleted, to inquire of the receiving terminal as to whether a request for re-uploading of the attachment is necessary, and in response to a response from the receiving terminal indicating a request for re-uploading, to notify the relay device 10 via the communication network NW of a re-upload instruction including attachment information indicating the content of the request for re-uploading.

[0034] The communication terminals 20 and 40 used by the email recipients are configured to access the file server 30 from a browser and, after successful authentication, download the desired attachment. During the download, various messages can be exchanged between the communication terminals and the file server 30. Figure 4 shows an example of a message screen for notifying the email recipient that the expiration date of the desired attachment has expired and that the attachment has been deleted. In this example, the message screen is used to inquire about whether a re-upload request is necessary, and if the email recipient presses the "Yes" button, a response is sent to the file server 30 requesting a re-upload.

[0035] [Operation of the first embodiment] Next, the operation of the file sharing system 1 according to the first embodiment will be described with reference to Figures 5 to 7. Here, an example will be described in which an email with an attachment is sent from communication terminal A (20), which is a sending terminal used by an email sender, to communication terminal X (40), which is a receiving terminal used by an email recipient, and communication terminal B (20, not shown).

[0036] As shown in the sequence diagram of Figure 5, when a mail transmission request for a mail with an attachment addressed to communication terminal X and communication terminal B is sent from communication terminal A to mail server 31 on communication network NW (step 100), control circuit 14 of relay device 10 receives the mail transmission request via LAN and communication I / F 11, separates the attachment from the mail with the attachment included in the mail transmission request (step 101), and sends a file UL request (file upload request) for the obtained attachment from communication I / F 11 to file server 30 via communication network NW (step 102).

[0037] In response to the file UL request from relay device 10, file server 30 saves the corresponding attachment (step 103), generates access information including link information, expiration date, and password for the saved attachment (step 104), and returns a file UL response (file upload response) including the obtained access information (step 105).

[0038] Control circuit 14 of relay device 10 acquires the access information from the file UL response returned from file server 30, adds the access information to the body of the separated email from which the attachment has been separated (step 106), and sends a mail transmission request for the separated email to mail server 31 via communication I / F 11 and communication network NW (step 107). As a result, the separated email including the access information is sent to communication terminal X and communication terminal B.

[0039] The control circuit 14 also stores in the memory circuit 13, in step 108, mail identification information, such as the sender's email address, the recipient's email address, and the message ID, relating to the email with the attachment, in association with the access information notified from the file server 30. This makes it possible to identify the request email information to be used when sending the email requesting re-uploading, based on the attachment information included in the re-upload instruction.

[0040] After that, when a mail reception request is sent from communication terminal X to mail server 31 (step 110), the post-separation mail from communication terminal A is notified as a received mail by a mail reception response (step 111).

[0041] In response to an operation by the email recipient on communication terminal X based on the access information contained in the received separated email, a file DL request (file download request) for the attached file is sent from communication terminal X to file server 30 via communication network NW (step 112). After this, authentication processing is performed between communication terminal X and file server 30 (step 113), and if the authentication is successful, the specified attached file is downloaded from file server 30 to communication terminal X by a file DL response (file download response) (step 114). As a result, the attached file from communication terminal A is shared at communication terminal X.

[0042] On the other hand, after the expiration date of the attached file has expired and the file server 30 has forcibly deleted it, as shown in the sequence diagram of Fig. 6, if a file DL request is sent from communication terminal X to file server 30 via communication network NW (step 120), authentication processing is performed between communication terminal X and file server 30 in the same manner as described above (step 121), and if the authentication is successful, a file DL response is sent from file server 30 to communication terminal X indicating that the specified attached file has expired and has been deleted (step 122).

[0043] At this time, as shown in the message screen of FIG. 4 described above, an inquiry is made as to whether a re-upload request is required (step 123), and if the email recipient presses the "Yes" button, a re-upload request is required and a re-upload response is sent from communication terminal X to file server 30 (step 124).

[0044] In response to the re-upload request response from communication terminal X, file server 30 notifies relay device 10 via communication network NW of a re-upload instruction including the attachment file information shown in Figure 3 above as information regarding the attachment file that needs to be re-uploaded (step 125).

[0045] When a re-upload instruction is notified from the file server 30, the control circuit 14 of the relay device 10 extracts link information of the attachment that needs to be re-uploaded from the attachment information included in the re-upload instruction, and based on the link information, obtains mail identification information such as the sender's email address, the recipient's email address, and the message ID from the memory circuit 13 as information for identifying the email with the attachment (step 126). Next, based on the obtained email identification information, the control circuit 14 generates a request email to request the email sender to resend the original email with the attachment (step 127), and sends an email transmission request regarding the obtained request email from the communication I / F 11 to the email server 31 via the communication network NW (step 128).

[0046] The sender of the email then receives the request email, checks the request, and resends the email with the specified attachment, which results in the attachment being shared via file server 30, in the same way as in Figure 5 above. That is, as shown in the sequence diagram of FIG. 7, when a mail reception request is sent from communication terminal A to mail server 31 (step 130), the request mail from relay device 10 is notified as a received mail by a mail reception response (step 131).

[0047] As a result, when a mail transmission request for the original mail with an attachment, with communication terminal X and communication terminal B as destinations, is sent from communication terminal A to mail server 31 on communication network NW in response to an operation by the mail sender (step 132), control circuit 14 of relay device 10 retrieves the mail transmission request via LAN and communication I / F 11, separates the attachment from the original mail with attachment included in the mail transmission request (step 133), and sends a file UL request for the obtained attachment from communication I / F 11 to file server 30 via communication network NW (step 134).

[0048] In response to the file UL request from relay device 10, file server 30 stores the corresponding attachment (step 135), generates access information including link information, expiration date, and password for the stored attachment (step 136), and returns a file UL response including the obtained access information (step 137).

[0049] Control circuit 14 of relay device 10 acquires the access information from the file UL response returned from file server 30, adds the access information to the body of the separated email from which the attachment has been separated (step 138), and transmits an email transmission request for the separated email to email server 31 via communication I / F 11 and communication network NW (step 139). As a result, the separated email including the access information is transmitted to communication terminal X and communication terminal B.

[0050] Therefore, after this, by performing operations similar to steps 110 to 114 in Figure 5, the re-uploaded attachment can be downloaded from file server 30 to communication terminal X, and the attachment from communication terminal A will be shared on communication terminal X. In this case, the original email with the attached file will be resent to all of the original recipient email addresses, so it will also reach recipients who have already downloaded the attachment. For this reason, as a consideration to such email senders, you may want to add a note to the body of the resent separated email that states that it is being resent to recipients who have not yet downloaded the attachment.

[0051] [Advantages of the first embodiment] In this way, in this embodiment, when a download request is made from the communication terminal 20, 40 used by the email recipient for an attachment that has been deleted due to expiration, the file server 30 inquires the email recipient who made the download request as to whether or not a re-upload request is required, and in response to the request for re-upload from the email recipient, the file server 30 instructs the relay device 10 to request a re-upload, and in response to this instruction, the relay device 10 sends an email requesting a re-upload to the email sender.

[0052] As a result, a request to re-upload an attachment that was deleted due to its expiration date is automatically notified to the email sender from file server 30 and relay device 10. Therefore, when an email recipient requests re-uploading of a deleted attachment, the email recipient only needs to request re-uploading from file server 30. This eliminates the need for the email recipient to perform the cumbersome task of requesting the email sender to resend the desired attachment by phone or email, as in the past, and makes it possible to request re-uploading from the email sender with an extremely small workload.

[0053] [Second embodiment] Next, a file sharing system 1 according to a second embodiment of the present invention will be described.

[0054] According to the first embodiment described above, when the sender of the original email with the attachment receives and confirms the request email for re-uploading, there is a possibility that the sender will resend the original email with the attachment as is. In this case, the original email with the attachment will be resent to all recipients specified as destinations in the original email with the attachment.

[0055] For example, as mentioned above, even if the destination of the original email with the attachment is communication terminal X or B and the recipient of the email at communication terminal B has already downloaded the attachment, the original email with the attachment will also arrive at communication terminal B in response to a resend of the original email with the attachment from communication terminal A in response to the request email. Therefore, while email recipients who have requested that the attachment be re-uploaded and those who have not yet downloaded the attachment will understand that the original email with the attachment has been resent, resending the email to those who have already downloaded the attachment may cause confusion or misunderstanding, resulting in a wasteful resend process.

[0056] In the file sharing system 1 according to the second embodiment, when an email with an original attachment is resent from the email sender in response to an email requesting re-uploading, the relay device 10 is configured to limit the re-sending destination to only the person who requested the re-upload of the attachment, or to people who have not yet downloaded the attachment. This makes it possible to limit the recipients of the original email with the attached file to those who have requested a re-upload of the attached file, or to those who have not yet downloaded the attached file, thereby avoiding the wasteful re-sending process described above.

[0057] That is, in the second embodiment, when the captured mail sending request is a mail sending request corresponding to a request mail, the control circuit 14 of the relay device 10 is configured to separate the attachment from the mail with the attachment included in the mail sending request and upload it to the file server 30, and based on the attachment information, to send a mail sending request for the separated mail to the mail server 31, with the destination being only the person who has requested to re-upload the attachment or the person who has not yet downloaded the attachment.

[0058] In this configuration, it is necessary to specify the email addresses of only those requesting a re-upload of the attachment, or those who have not yet downloaded the attachment. However, the email addresses of those requesting a re-upload of the attachment and those who have already downloaded the attachment can be obtained by the file server 30, and can be notified to the relay device 10 by a re-upload instruction sent from the file server 30. In particular, the email addresses of those who have not yet downloaded the attachment can be obtained as the remaining email addresses by excluding the email addresses of those who have already downloaded the attachment from the destination addresses of the original email with the attachment. Note that secondary destination email addresses such as CC (Carbon Copy) and BCC (Blind Carbon Copy) in the original email with the attachment may be excluded from the re-sending destinations.

[0059] Generally, the file server 30 manages access rights to ensure security, and each user must register a user account in advance to access the file server 30. Therefore, if an email address is registered in association with a user account, the email address of the accessing user can be identified.

[0060] Specifically, when a mail recipient accesses the file server 30 from a receiving terminal, an authentication process is first performed to confirm access rights, and the user account of the mail recipient is identified through this authentication process.

[0061] After this, the specified attachment becomes available for download as long as it is within the expiration date. Therefore, when an attachment is downloaded by a mail recipient, the file server 30 can obtain the email address from the user account of the mail recipient, and can store this as the email address of the person who has already downloaded the attachment for each attachment.

[0062] On the other hand, if the specified attachment has expired and been forcibly deleted, the attachment will no longer be available for download. Therefore, when the file server 30 determines that the attachment is unavailable for download, it can obtain the email address from the user account of the email recipient and store it as the email address of the person requesting the re-upload of the attachment.

[0063] Thereafter, file server 30 inquires of the receiving terminal as to whether a request for re-uploading of the aforementioned attached file is necessary, and in response to a response from the receiving terminal indicating a request, notifies relay device 10 of a re-upload instruction including attachment file information indicating the content of the re-upload request. Therefore, the previously stored email addresses of the person requesting the re-upload and the person who has already downloaded the file can be included in the attachment file information and notified to relay device 10.

[0064] [Third embodiment] Next, a file sharing system 1 according to a third embodiment of the present invention will be described.

[0065] According to the first and second embodiments described above, the relay device 10 sends a request email to the sender of the original email with the attached file, and the sender is asked to resend the original email with the attached file. This may result in a burden on the sender of the email.

[0066] In the file sharing system 1 according to the third embodiment, emails with attachments are stored in the memory circuit 13 of the relay device 10, and when a re-upload instruction is received from the file server 30, the control circuit 14 of the relay device 10 retrieves the email with the attachment corresponding to the re-upload instruction from the memory circuit 13 and resends it. As a result, the attachment is shared via the file server 30, as in the case of Fig. 5 described above, and the burden on the email sender that would be incurred when resending the original email with the attachment can be avoided.

[0067] At this time, the control circuit 14 needs to identify the original email with the attached file corresponding to the re-upload instruction from among the emails with attached files stored in the memory circuit 13.

[0068] In this regard, when storing an email with an attachment in the memory circuit 13, if the link information notified from the file server 30 in the access information is linked to the email with the attachment, it is possible to identify the original email with the attachment that matches the link information included in the re-upload instruction.

[0069] In addition, when uploading an attachment, the file server 30 may link the email ID of the original email with the attachment, which is notified by the relay device 10, to the attachment, and when sending a re-upload instruction, may notify the email ID corresponding to the attachment, and the control circuit 14 may retrieve the corresponding original email with the attachment from the memory circuit 13 based on the email ID notified by the file server 30.

[0070] Furthermore, a storage expiration date may be set for each email with an attachment stored in the memory circuit 13 of the relay device 10, and email with an attachment that has reached the expiration date may be forcibly deleted. Note that this storage expiration date must be longer than the expiration date of the attachment in the file server 30. This allows the storage capacity of the memory circuit 13 to be used effectively.

[0071] [Extended embodiment] Although the present invention has been described above with reference to the embodiments, the present invention is not limited to the above embodiments. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention. Furthermore, the respective embodiments can be implemented in any combination within a consistent range.

[0072] In the first to third embodiments described above, a request validity period during which a request for re-uploading of an attachment file can be set. For example, the request validity period may be set to one month from the expiration date of the attachment file, and re-upload requests may no longer be possible upon expiration of the request validity period. Furthermore, the presence or absence of a request validity period and the length of the period may be set for each email sender of the original email with an attachment file, or the system settings may be applied uniformly to all email senders.

[0073] In the first to third embodiments described above, the file server 30 may inquire of the person requesting re-upload of the attached file as to whether or not re-uploading is necessary through the control circuit 14 of the relay device 10 .

[0074] Specifically, for example, if communication terminal X is notified of the expiration date in step 122 of Figure 6, steps 123 and 124 are skipped, and in the same manner as described above, in response to a re-upload instruction from file server 30 (step 125), control circuit 14 of relay device 10 obtains mail identification information from memory circuit 13 (step 126).

[0075] Next, the control circuit 14 may generate an inquiry email based on the obtained email identification information to inquire whether re-uploading is necessary, and send it to the person who requested re-uploading of the attached file.If the response indicates that re-downloading is necessary, the control circuit 14 may proceed to step 127. This simplifies the configuration and processing of the file server 30. In this case, the inquiry email may be sent to all email senders of the original email with the attached file, or may be sent only to those who have not yet downloaded the attached file, using a partial configuration of the second embodiment described above. [Explanation of symbols]

[0076] 1...file sharing system, 10...relay device, 11...communication I / F, 12...UTM processing circuit, 13...memory circuit, 14...control circuit, 20, A, B...communication terminal, 30...file server, 31...mail server, 40, X...communication terminal, L1...communication line, NW...communication network.

Claims

1. a relay device connected to a communication network and configured to relay and connect a communication terminal connected thereunder via a LAN to the communication network; a file server connected to the communication network and configured to check the expiration date of each uploaded file and delete files whose expiration date has expired; Equipped with The relay device the communication terminal is configured to receive a mail transmission request for an email with an attachment, the mail transmission request being sent from a sending terminal used by an email sender among the communication terminals to a mail server on the communication network, separate the attachment from the email with the attachment included in the mail transmission request, upload the attachment to the file server, and send a mail transmission request for the separated email from which the attachment has been separated to the mail server; The file server the method is configured to check the specified attachment file in response to a download request from a receiving terminal used by a recipient of the separated email, and download the specified attachment file; The file server if the attachment has expired and been deleted, the receiving terminal is inquired as to whether a request for re-uploading of the attachment is necessary, and in response to a response from the receiving terminal indicating a request for re-uploading, the relay device is notified of a re-upload instruction including attachment information indicating the content of the request for re-uploading; The relay device In response to a re-upload instruction from the file server, an email transmission request is sent to the email server, requesting the email sender of the specified attachment to re-upload the attachment based on the attachment information included in the re-upload instruction. File sharing system.

2. The relay device When the captured email transmission request is an email transmission request in response to the re-upload instruction, the attachment is separated from the email with the attachment included in the email transmission request, and uploaded to the file server, and an email transmission request for the separated email, whose destination is only the person who requested the re-upload of the attachment, is transmitted to the email server based on the attachment information included in the re-upload instruction. The file sharing system according to claim 1 .

3. The relay device When the captured mail transmission request is a mail transmission request in response to the re-upload instruction, the attachment is separated from the mail with the attachment included in the mail transmission request and uploaded to the file server, and a mail transmission request for the separated mail, addressed to those who have not yet downloaded the attachment, is transmitted to the mail server based on the attachment information included in the re-upload instruction. The file sharing system according to claim 1 .

4. The relay device The captured mail transmission requests are stored in a storage circuit, and in response to a re-upload instruction from the file server, a corresponding mail transmission request is acquired from the storage circuit based on the attachment file information included in the re-upload instruction, the destination of the mail included in the mail transmission request is changed to only the source of the re-upload request for the attachment file specified in the attachment file information, and the mail transmission request for the changed mail with the attachment file attached is transmitted to the mail server. The file sharing system according to claim 1 .

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