Patent Publication Number: US-11050719-B2

Title: Systems and methods for controlling email access

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 16/279,624, filed Feb. 19, 2019, which is a continuation of application Ser. No. 15/664,279, filed Jul. 31, 2017, which is a continuation of Ser. No. 15/242,752, filed Aug. 22, 2016, which is a continuation of application Ser. No. 14/337,338, filed Jul. 22, 2014, which is a continuation of application Ser. No. 13/706,817, filed on Dec. 6, 2012, which is a continuation-in-part of application Ser. No. 13/706,499, filed on Dec. 6, 2012. The patent applications identified above are incorporated herein by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     Embodiments of the disclosure relate generally to data security, and more particularly, to systems and methods for controlling email access. 
     BACKGROUND 
     Controlling email access is critical to ensure that email resources may only be accessed by authorized parties in authorized manners. To date, enterprises have utilized access credentials to control which, if any, parties may access email resources. This method may ensure that only authorized parties may access email resources. However, this method fails to control how those email resources may be accessed by the proper recipients. This method further fails to modify the email resources to comply with enterprise security standards. As enterprises seek to protect sensitive information, systems and methods for controlling email access are necessary to ensure that email resources may only be accessed by authorized parties in authorized manners. 
     BRIEF SUMMARY 
     Some or all of the above needs and/or problems may be addressed by certain embodiments of the disclosure. Certain embodiments may include systems and methods for controlling access to networks. According to one embodiment of the disclosure, there is disclosed a system. The system can include one or more client devices. The system can also include one or more email services. The system can further include a memory that stores computer-executable instructions. The system can yet further include a processor configured to access the at least one memory. The processor is configured to execute the computer-executable instructions to perform a method including the steps of proxying one or more email resources in transit to the client devices from the email services, removing one or more email attachments from the email resources, and encoding the stripped email attachments based at least in part on one or more cryptographic keys. 
     According to another embodiment of the disclosure, there is disclosed a method. The method can include identifying, on one or more client devices, one or more encoded email resources, identifying one or more cryptographic keys associated with the encoded email resources, and decoding the encoded email resources based at least in part on one or more cryptographic keys. 
     Further, according to another embodiment of the disclosure, there is disclosed a non-transitory computer-readable medium embodying a program executable in a computing device, the program comprising code that, when executed by a computing device, causes the computing device to perform a method comprising the steps of identifying one or more email resources associated with one or more client devices, modifying one or more portions of the email resources, and authorizing the client devices associated with the email resources to access the email resources. 
     Other embodiments, systems, methods, apparatus aspects, and features of the disclosure will become apparent to those skilled in the art from the following detailed description, the accompanying drawings, and the appended claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description is set forth with reference to the accompanying drawings, which are not necessarily drawn to scale. The use of the same reference numbers in different figures indicates similar or identical items. 
         FIG. 1  illustrates a block diagram of a networked environment according to certain embodiments of the disclosure. 
         FIG. 2  illustrates a flow diagram of exemplary functionality performed by an access control service executed by an access control server in the networked environment of  FIG. 1  according to certain embodiments of the present disclosure. 
         FIG. 3  illustrates a flow diagram of exemplary functionality performed by a client side application executed by a client device in the networked environment of  FIG. 1  according to certain embodiments of the present disclosure. 
         FIGS. 4-5  are exemplary user interfaces rendered by an access control service executed by an access control server in the networked environment of  FIG. 1  according to certain embodiments of the present disclosure. 
         FIGS. 6-11  are exemplary user interfaces rendered by a client side application executed by a client device in the networked environment of  FIG. 1  according to certain embodiments of the present disclosure. 
         FIG. 12  illustrates a block diagram of a networked environment according to certain embodiments of the disclosure. 
         FIG. 13  illustrates a flow diagram of exemplary functionality performed by an access control service executed by an access control server in the networked environment of  FIG. 12  according to certain embodiments of the present disclosure. 
         FIG. 14  illustrates a block diagram of a networked environment according to certain embodiments of the disclosure. 
         FIG. 15  illustrates a flow diagram of exemplary functionality performed by an access control service executed by an access control server in the networked environment of  FIG. 14  according to certain embodiments of the present disclosure. 
         FIG. 16  illustrates a flow diagram of exemplary functionality performed by a client side application executed by a client device in the networked environment of  FIGS. 12 and 14  according to certain embodiments of the present disclosure. 
         FIG. 17  illustrates schematic block diagrams of an access control server and a client device employed in the network environments of  FIGS. 1, 12 and 14  according to certain embodiments of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Illustrative embodiments of the disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the disclosure are shown. The disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. As noted above, like numbers refer to like elements throughout. 
     Illustrative embodiments of the disclosure are directed to, among other things, controlling access to email. As an overview, access to email may be controlled by limiting access of proper recipients to specific email resources and by limiting the manner in which the proper recipients access the specific email resources. In certain embodiments, the email resources may be modified to satisfy access restrictions. 
     The technical effects of certain embodiments of the disclosure may include preventing unauthorized access to email resources and eliminating costs associated with sensitive information loss. Moreover, the technical effects of certain embodiments of the invention may include modifying email resources to satisfy access restrictions. 
       FIG. 1  depicts certain illustrative components for a networked environment  100  according to various embodiments. In certain embodiments, the networked environment  100  may include a network  110 , a client device  120 , and an access control server  150 . In some embodiments, the network  110  may be or include, for example, any type of wireless network such as a wireless local area network (WLAN), a wireless wide area network (WWAN), and/or the like. Additionally, the network  110  may be or include the Internet, intranets, extranets, microwave networks, satellite communications, cellular systems, PCS, infrared communications, global area networks, and/or any combination of two or more such networks. In one embodiment, the network  110  facilitates access to email resources  165  for one or more client devices  120 , where access to the email resources  165  is controlled by an access control server  150 . 
     The client device  120  may comprise, for example, a cellular telephone, a smartphone and/or personal digital assistant, a tablet computer and/or web pad, a laptop computer, a desktop computer, a set-top box, a music player, a game console, and/or another device with like capability. For purposes of convenience, the client device  120  is referred to herein in the singular. Even though the client device  120  is referred to in the singular, it is understood that one or more client devices  120  may be employed in the arrangements as descried herein. 
     The client device  120  may include a wired network connectivity component (not shown in  FIG. 1 ), for example, an Ethernet network adapter, a modem, and/or the like. The client device  120  may further include a wireless network connectivity interface (not shown in  FIG. 1 ), for example, a PCI (Peripheral Component Interconnect) card, USB (Universal Serial Bus) interface, PCMCIA (Personal Computer Memory Card International Association) card, SDIO (Secure Digital Input-Output) card, NewCard, Cardbus, a modem, a wireless radio transceiver, and/or the like. The client device  120  may be operable to communicate via wired connection with the access control server  150  with the aid of the wired network connectivity component. The client device  120  may be further operable to communicate wirelessly with the access control server  150  with the aid of the wireless network connectivity component. 
     The client device  120  may comprise a memory for storing data and applications, a processor for executing applications stored in memory, a display  136  upon which the processor may execute one or more user interfaces  137 , and a local interface such as a bus, as will be described with respect to  FIG. 12 . The memory of the client device  120  may comprise a data store  122 . The data store  122  of the client device  120  may include a device profile  123 . In one embodiment, the device profile  123  may represent hardware, software, and security attributes that describe the state of the client device  120 . For instance, the device profile  123  may represent hardware specifications of the client device  120 , version and configuration information of various software programs and hardware components installed on the client device  120 , transport protocols enabled on the client device  120 , version and usage information of various other resources stored on the client device  120 , and/or any other attributes associated with the state of the client device  120 . In another embodiment, the device profile  123  may further include characteristics describing the state of the client device  120 , including indications of the location of the client device  120 , the current time associated with the client device  120 , the client device&#39;s  120  detection of one or more network beacons associated with one or more networks  110 , and the signal strength of the network beacons received by the client device  120 . In yet another embodiment, the device profile  123  may include data indicating a date of a last virus scan of the client device  120 , a date of a last access and/or service by an Information Technology (IT) representative, a date of a last access by an access control service  174 , and/or any other data indicating a date of last maintenance of the client device  120 . 
     Additionally, the data store  122  of the client device  120  may include one or more user identifiers  132 . The user identifiers  132  may uniquely identify the user of the client device  120 . In one embodiment, the user identifiers  132  may include a username, a password, and/or biometric data related to facial recognition, retina recognition, fingerprint recognition, and the like. Similarly, the data store  122  of the client device  120  may include one or more device identifiers  135 . The device identifiers  132  may uniquely identify the client device  120 . In one embodiment, the device identifiers  135  may be a unique hardware identifier such as a GUID (Globally Unique Identifier), UUID (Universally Unique Identifier), UDID (Unique Device Identifier), serial number, IMEI (Internationally Mobile Equipment Identity), Wi-Fi MAC (Media Access Control) address, Bluetooth MAC address, a CPU ID, and/or the like, or any combination of two or more such hardware identifiers. In another embodiment, the device identifier  135  may be a unique software identifier such a token or certificate, based at least in part on the aforementioned unique hardware identifiers. 
     The client device  120  may be configured to execute various applications. For example, the client device  120  may be configured to execute applications such as secure container applications, web browsing applications, email applications, instant messaging applications, word processing applications and/or other applications capable of receiving and/or rendering resources  165  on a display  136  associated with the client device  120 . Any application capable of receiving and/or rendering resources  165  on a display  136  of the client device  120  is generally referred to herein as a “client side application”  126 . The client side application  126  may be stored in the memory of the client device  120 . In one embodiment, the client side application  126  may be a secure container application that may be authorized to receive and render resources  165  in accordance with one or more resource rules  171 , as described herein. The client side application  126  may include a cryptographic key to decrypt email resources  165  encrypted with a cryptographic key in order to prevent unauthorized access to the email resources  165 . For instance, the client side application  126  may have a cryptographic key that may be capable of decrypting email resources  165  transmitted in an encrypted format to the client device  120  by an access control service  174  executed by an access control server  150 . 
     The client side application  126  may be executed to transmit one or more requests  177  to access one or more email resources  165 . In certain embodiments, the client side application  126  may transmit requests  177  to an access control service  174 . In some embodiments, the requests  177  may include a listing of specific email resources  165  the client device  120  seeks to access. In other embodiments, the requests  177  may include an indication that the client device  120  seeks access to email resources  165  associated with the client device  120 , such as email resources  165  addressed to the user of the client device  120 . In any instance, the requests  177  may include data from the data store  122  of the client device  120  that may assist an access control service  174  in determining whether the client device  120  is authorized to access the email resources  165 . In one embodiment, the request  177  may include the device profile  123  associated with the client device  120 . In another embodiment, the request  177  may include user identifiers  132  associated with the client device  120 . In yet another embodiment, the request  177  may include device identifiers  135  associated with the client device  120 . 
     The client side application  126  may be further executed to receive an indication that the client device  120  is authorized to access the email resources  165 . In certain embodiments, the client side application  126  may receive an authorization indication from an access control service  174  executed by an access control server  150 . In some embodiments, the authorization indication may specify which, if any, email resources  165  that the client device  120  is authorized to access and may specify the manner in which the client device  120  may access such email resources  165 . In one embodiment, the authorization indication may specify that the client device  120  is authorized to access the email resources  165  while the client device  120  is located within one or more authorized locations. In another embodiment, the authorization indication may specify that the client device  120  is authorized to access the email resources  165  while the current time associated with the client device  120  is within one or more authorized windows. In yet another embodiment, the authorization indication may specify that the client device  120  is authorized to access the email resources  165  while the client device  120  is communicatively connected to one or more networks  110  and/or one or more network beacons associated with the networks  110 , as described in application Ser. No. 13/656,046 entitled “SYSTEMS AND METHODS FOR CONTROLLING NETWORK ACCESS,” which is incorporated herein by reference in the entirety. 
     The client side application  126  may be further executed to receive one or more email resources  165 . In certain embodiments, the client side application  126  may receive email resources  165  from an access control service  174  executed by an access control server  150 . In some embodiments, the client side application  126  may receive email resources  165  from an enterprise email service, such as Microsoft Exchange, Lotus Notes, Novell Groupwise, Zimbra, or the like. In other embodiments, the client side application  126  may receive email resources  165  from a distribution service executed by a distribution server, as described in application Ser. Nos. 13/396,356 and 13/623,627 both entitled “CONTROLLING DISTRIBUTION OF RESOURCES ON A NETWORK,” which are incorporated herein by reference in their entirety. 
     In any instance, the email resources  165  may include various types of electronic data, such as email messages and email attachments. In certain embodiments, the email messages may include text and/or formatting in email headers, email sender fields, email recipient fields, email subject fields, email bodies, email signatures, and/or email footers. Additionally, the email attachments may include settings-type attachments, applications-type attachments, and content-type attachments. In one embodiment, settings-type attachments may include hardware settings, software settings, and/or the like that configure the functionality provided by the client device  120 . In another embodiment, application-type attachments may include book applications, business applications, catalogue applications, education applications, entertainment applications, finance applications, food and drink applications, games applications, health and fitness applications, lifestyle applications, medical applications, music applications, navigation applications, news applications, newsstand applications, photo and video applications, productivity applications, reference applications, social networking applications, sports applications, travel applications, utility applications, weather applications, and/or the like. In yet another embodiment, content-type attachments may include application content, video content, image content, audio content, text content, word processor content, presentation content, spreadsheet content, database content, compressed folder content, disk image content, encoded content, backup content, web content, page layout content, plug-in content, font content, system content, developer content, data content and/or the like. 
     The client side application  126  may be similarly executed to receive one or more resource rules  171  associated with the email resources  165 . In certain embodiments, the resource rules  171  may regulate user of and/or access to the email resources  165 . In some embodiments, the resource rules  171  may include format rules, content rules, attachment rules, and/or access rules. In one embodiment, the format-type resource rules  171  may specify one or more of required, permitted, and/or prohibited formats of the email resources  165 . For example, a format-type resource rule  171  may specify that all email resources  165  must be encoded with AES-256 bit encryption. In another embodiment, the content-type resource rules  171  may specify one or more of required, permitted, and/or prohibited content of the email resources  165 . For instance, a content-type resource rule  171  may specify that any email resources  165  containing the text “confidential” must be transmitted utilizing a secure transmission protocol, such as the HTTPS/SSL transmission protocol. In yet another embodiment, the attachment-type resource rules  171  may specify one or more of required, permitted, and/or prohibited attachments to the email resources  165 . For example, an attachment-type resource rule  171  may specify that attachments to the email resources  165  must be stripped from the email resources  165 . In yet a further embodiment, the access-type resource rules  171  may specify one or more of required, permitted, and/or prohibited access to the email resources  165 . For instance, an access-type resource rule  171  may specify that the email resources  165  must be configured to be exclusively accessible via a secure container application, such as the client side application  126 . Furthermore, the various types of resource rules  171  may be combined to establish granular access rights. For example, a combination of resource rules  171  may specify required attachment format, attachment content, and attachment access. 
     In some embodiments, the resource rules  171  may be metadata and/or other indications that describe the email resources  165 . In particular, the resources rules  171  may specify categories/sub-categories to which the email resources  165  belong, that the email resources  165  are considered favorites, the ownership of the email resources  165 , the managing party of the email resources  165 , that the email resources  165  are confidential, that the email resources  165  are password protected, the historical version of the email resources  165 , one or more descriptions of the email resources  165 , one or more comments regarding the email resources  165 , the size and format of the email resources  165 , the download priority associated with the email resources  165 , an expiration date associated with the email resources  165 , one or more effective dates associated with the email resources  165 , and/or the like. 
     In other embodiments, the resource rules  171  associated with the email resources  165  may change based on the state of the client device  120 . In certain embodiments, the stringency of the resource rules  171  may be increased, reduced, and/or eliminated based on the state of the client device  120 . In one embodiment, the stringency of the resource rules  171  may be increased, reduced, and/or eliminated if the client device  120  is located within the transmission range of certain network beacons and/or certain networks  110  associated with such network beacons. In another embodiment, the stringency of the resource rules  171  may be increased, reduced, and/or eliminated if the client device  120  is located within one or more locations. In yet another embodiment, the stringency of the resource rules  171  may be increased, reduced, and/or eliminated if the current time associated with the client device  120  is within one or more time windows. In yet a further embodiment, the stringency of the resource rules  171  may be increased, reduced, and/or eliminated if the client device  120  has previously satisfied the resource rules  171 . 
     Additionally, the client side application  126  may be executed to determine whether the client device  120  is authorized to access the email resources  165 . In certain embodiments, the client side application  126  may determine whether the resource rules  171  associated with the email resources  165  are satisfied by the email resources  165 . For instance, the client side application  126  may determine that the client device  120  is authorized to access the email resources  165  if the attachments to the email resources  165  have been stripped from the email resources  165  in accordance with the resource rules  171  associated with the email resources  165 , which specify that the email resources  165  may not have attachments. In some embodiments, the client side application  126  may determine whether the client device is authorized based at least in part on one or more of the device profile  123 , user identifiers  132 , or device identifiers  135 . 
     The client side application  126  may be further executed to modify the email resources  165 . In certain embodiments, the client side application  126  may modify the email resources  165  in response to a determination that the email resources  165  do not satisfy the resource rules  171  associated with the email resources  165 . In particular, the client side application  126  may modify the email resources  165  so that the email resources  165  satisfy the resource rules  171  associated with the email resources  165 . In some embodiments, the client side application  126  may modify one or more portions of the email resources  165 . In other embodiments, the client side application  126  may modify all portions of and/or the entirety of the email resources  165 . 
     In any instance, the client side application  126  may modify the email resources  165  by formatting, encoding, configuring, adding, removing, stripping, moving, replacing and/or flagging portions of the email resources. In one embodiment, the client side application  126  may modify the email resources  165  by formatting the email resources  165  into HyperText Markup Language (HTML) Rich Text, Plain Text, and/or other formats. In another embodiment, the client side application  126  may modify the email resources  165  by encoding the email resources  165  using Advanced Encryption Standard (AES), Data Encryption Standard (DES), and/or other encryption protocols. In yet another embodiment, the client side application  126  may modify the email resources  165  by configuring the email resources  165  to be exclusively accessible via one or more secure container applications, such as the client side application  126 . In yet a further embodiment, the client side application  126  may modify the email resources  165  by adding portions to and/or or removing portions from the email resources  165 , for instance, by adding or removing an email signature. 
     Additionally, in an exemplary embodiment, the client side application  126  may modify the email resources  165  by removing portions of the email resources  165  and configuring the removed portions of the email resources  165  to be exclusively accessible via a secure container application, such as the client side application  126 . For example, the client side application  126  may remove attachments from the email resources  165  and may encode the removed attachments based at least in part on one or more cryptographic keys accessible to the client side application  126 . In another embodiment, the client side application  126  may modify the email resources  165  by performing one or more of decrypting the email resources  165 , re-encrypting the email resources  165 , cryptographically signing email resources  165 , or re-signing email resources  165 . In yet another embodiment, the client side application  126  may modify the email resources  165  by moving certain portions of the email resources  165 , such as by moving a photograph from the body of the email resources  165  to the attachments of the email resources  165 . In yet a further embodiment, the client side application  126  may modify the email resources  165  by replacing certain portions of the email resources  165 , such as replacing misspelled text with the properly spelled text. In even yet a further embodiment, the client side application  126  may modify the email resources  165  by flagging the email resources  165  as having been modified, such as by attaching an indication to the email resources  165  that provides information related to the modification of the email resources  165 . 
     The client side application  126  may be yet further executed to access one or more email resources  165 . In certain embodiments, the client side application  126  may access the email resources  165  received from an access control service  174  and/or another distribution service. In some embodiments, the client side application  126  may access the email resources  165  on the client device  120  in accordance with the resource rules  171 . For example, the client side application  126  may determine that the email resources  165  may not be accessed by the client device  120  because the client device  120  is not located within an authorized location specified by the resource rules  171  associated with the email resources  165 . 
     In any instance, the client side application  126  may access the email resources  165  on the client device  120  by storing, installing, activating, rendering and/or executing the email resources  165  on the client device  120 . In one embodiment, the client side application  126  may store the email resources  165  on the client device  120  by placing the email resources  165  in the data store  122  of the client device  120 . In another embodiment, the client side application  126  may install the email resources  165  on the client device  120  by placing the email resources  165  in the data store  122  of the client device  120  and by disabling and/or removing any files that conflict with the email resources  165 . In yet another embodiment, the client side application  126  may activate the email resources  165  on the client device  120  by placing the email resources  165  in the data store  122  of the client device  120 , by disabling and/or removing any files that conflict with the email resources  165 , and by instructing the client device  120  to conform its operations to the email resources  165 . Additionally, the client side application  126  may call on other applications and/or services accessible to the client device  120  that are associated with the email resources  165 . 
     In yet a further embodiment, the client side application  126  may render the email resources  165  on the client device  120  by presenting the email resources  165  in a user interface  137  executed on the display  136  of the client device  120 . In particular, the client side application  126  may render the email resources  165  in a user interface  137  by decompressing compressed files and presenting the uncompressed files, mounting disk image files and presenting the mounted image files, running executable files and presenting the executed files, by enabling a data search of the email resources  165  and presenting the featured output in a user interface  137 , by calling on another application on the client device  120  to respond to data links contained within the email resources  165 , and/or by transmitting a part or the whole of the email resources  165  to another application on the client device  120 . The client side application  126  may render a single email resource  165  or a series of email resources  165  in a comprehensive manner, such as presenting image files in a slideshow-style presentation, and may further render an environment that displays an array of email resources  165  in a single view, such as a category-based tree or outline format. Additionally, in an exemplary embodiment, the client side application  126  may execute the email resources  165  by placing the email resources  165  in the data store  122  of the client device  120 , by disabling and/or removing any files that conflict with the email resources  165 , and by instructing the client device  120  to perform the operations of the email resources  165 . 
     In certain embodiments, the client side application  126  may be a secure container application that is configured to protect the email resources  165  from unauthorized access. In some embodiments, the client side application  126  may be configured to protect email resources  165  that have been received from an access control service  174 . In one embodiment, the client side application  126  may be executed to enforce the resource rules  171  and/or other metadata associated with the email resources  165 . For instance, the client side application  126  may prohibit cutting, copying, pasting, transmitting, emailing, text messaging, screen capturing, and/or otherwise manipulating the email resources  165  while the email resources  165  are accessed by the client side application  126 . In another embodiment, the client side application  126  may prohibit other applications on the client device  120  and/or other services accessible to the client device  120  from accessing the email resources  165 . In particular, the client side application  126  may monitor the data stream between the network  110  and the client device  120 , may block any access attempts by another application and/or service, may proxy the email resources  165 , and may present the proxyied email resources  165  in a user interface  137  rendered by the client side application  126 . 
     The access control server  150  may comprise, for example, a server computer or any other system providing access control capability. Alternatively, a plurality of access control servers  150  may be employed that are arranged, for example, in one or more server banks or computer banks or other arrangements. For example, a plurality of access control servers  150  together may comprise a cloud computing resource, a grid computing resource, and/or any other distributed computing arrangement. Such access control servers  150  may be located in a single installation or may be distributed among many different geographic locations. For purposes of convenience, the access control server  150  is referred to herein in the singular. Even though the access control server  150  is referred to in the singular, it is understood that a plurality of access control servers  150  may be employed in the arrangements as descried herein. 
     The access control server  150  may comprise a memory for storing data and applications and a processor for executing applications stored in memory, as will be described with respect to  FIG. 12 . The memory of the access control server  150  may comprise a data store  153 . The data store  153  may be representative of one or more data stores. The data store  153  may contain certain data that is accessible to the access control server  150 . In particular, the data store  153  may contain one or more email resources  165  and one or more resource rules  171  associated with the email resources  165 , as described herein. The data in the data store  153  may be associated with the operation of certain applications and/or functionalities executed by the access control server  150 . The data store  153  may utilize strong encryption standards to protect the email resources  165  from unauthorized access. For example, the data store  153  may utilize AES (Advanced Encryption Standard) or a similar strong encryption standard commonly utilized for server-side data storage. 
     The access control server  150  may execute certain applications and/or functionalities such the access control service  174 , as well as other applications, services, processes, systems, engines, or functionality not disclosed in detail herein. The access control service  174  may be executed to control email access. In particular, the access control service  174  may limit access to one or more email resources  165  to one or more client devices  120  that are authorized to access the email resources  165 . The access control service  174  may be further executed to modify one or more email resources  165  so that the email resources  165  satisfy one or more resource rules  171  associated with the email resources  165 . The access control service  174  may yet be further executed to distribute one or more email resources  165  to one or more client devices  120  that are authorized to access the email resources  165 . 
     The access control service  174  may be executed to control access to one or more email resources  165 . In certain embodiments, the access control service  174  may be executed to determine whether one or more client devices  120  are authorized to access the email resources  165 . In some embodiments, the client side application  126  may determine whether the resource rules  171  associated with the email resources  165  are satisfied by the email resources  165 . For instance, the access control service  174  may determine that a client device  120  is authorized to access the email resources  165  if the attachments to the email resources  165  have been stripped from the email resources  165  in accordance with the resource rules  171 , which specify that the email resources  165  may not have attachments. In other embodiments, the access control service  174  may determine whether the client device is authorized based at least in part on one or more of the device profile  123 , user identifiers  132 , or device identifiers  135 . 
     The access control service  174  may be further executed to modify the email resources  165  to satisfy the resource rules  171  associated with the email resources  165 . In certain embodiments, the access control service  174  may modify the email resources  165  in response to a determination that the email resources  165  do not satisfy the resource rules  171  associated with the email resources  165 . In particular, the access control service  174  may modify the email resources  165  so that the email resources  165  satisfy the resource rules  171  associated with the email resources  165 . In some embodiments, the access control service  174  may modify one or more portions of the email resources  165 . In other embodiments, the access control service  174  may modify all portions of and/or the entirety of the email resources  165 . 
     In any instance, the access control service  174  may modify the email resources  165  by formatting, encoding, configuring, adding, removing, stripping, moving, replacing or flagging portions of the email resources. In one embodiment, the access control service  174  may modify the email resources  165  by formatting the email resources  165  into HyperText Markup Language (HTML), Rich Text, Plain Text, and/or other formats. In another embodiment, the access control service  174  may modify the email resources  165  by encoding the email resources  165  using Advanced Encryption Standard (AES), Data Encryption Standard (DES), and/or other encryption protocols. In yet another embodiment, the access control service  174  may modify the email resources  165  by configuring the email resources  165  to be exclusively accessible via one or more secure container applications, such as a client side application  126 . In yet a further embodiment, the access control service  174  may modify the email resources  165  by adding portions to and/or or removing portions from the email resources  165 , for instance, by adding or removing an email signature. 
     Additionally, in an exemplary embodiment, the access control service  174  may modify the email resources  165  by removing portions from the email resources  165  and configuring the removed portions of the email resources  165  to be exclusively accessible via a secure container application, such as the client side application  126 . For example, the access control service  174  may remove attachments to the email resources  165  from the email resources  165 , may encode the removed attachments based at least in part on one or more cryptographic keys, and may make the removed attachments and cryptographic keys accessible to the client side application  126 . In another embodiment, the access control service  174  may modify the email resources  165  by performing one or more of decrypting the email resources  165 , re-encrypting the email resources  165 , cryptographically signing email resources  165 , or re-signing email resources  165 . In yet another embodiment, the access control service  174  may modify the email resources  165  by moving certain portions the email resources  165 , such as by moving a photograph from the body of the email resources  165  to the attachments of the email resources  165 . In yet a further embodiment, the access control service  174  may modify the email resources  165  by replacing certain portions of the email resources  165 , such as replacing misspelled text with the properly spelled text. In even yet a further embodiment, the access control service  174  may modify the email resources  165  by flagging the email resources  165  as having been modified, such as attaching an indication to the email resources  165  that provides information related to the modification of the email resources  165 . 
     The access control service  174  may be yet further executed to transmit one or more email resources  165  to one or more client devices  120 . In certain embodiments, the access control service  174  may transmit the email resources  165  to the client devices  120  responsive to a determination that the client devices  120  are authorized to access the email resources  165 . In some embodiments, the access control service  174  may transmit the email resources  165  to the client devices  120  responsive to modifying the email resources  165  to satisfy the resource rules  171  associated with the email resources  165 . In one embodiment, the access control service  174  may directly transmit the email resources  165  to a client side application  126  executed by the client devices  120 . In another embodiment, the distribution service  174  may make the email resources  165  available for download by the client devices  120  and may transmit the email resources  165  to the client devices  120  upon receiving requests  177  to download the email resources  165  from the client devices  120 . In any instance, the access control service  174  may establish a communicative connection with the client devices  120  by utilizing a secure transmission protocol, such as HTTPS/SSL, before transmitting the email resources  165  to the client devices  120 . 
       FIG. 2  is a flowchart illustrating exemplary functionality performed by an access control service  174  executed by an access control server ( FIG. 1 ) according to certain embodiments. It is understood that the flowchart of  FIG. 2  provides merely an example of the many different types of functional arrangements that may be employed to implement the operation of the access control service  174  as described herein. As an alternative, the flowchart of  FIG. 2  may be viewed as depicting an example of steps of a method implemented in the access control server  150  according to one or more embodiments. 
     Beginning with step  203 , the access control service  174  may identify one or more email resources  165 . In certain embodiments, the access control service  174  may identify one or more email resources  165  associated with one or more client devices  120 . In one embodiment, the email resources  165  may be associated with the client devices  120  if the email resources  165  are addressed to the client devices  120  and/or the users of the client devices  120 . For instance, the email resources  165  may be addressed to the client devices  120  and/or the users of the client devices  120  if the identities of the client devices  120  and/or the users of the client devices  120  are specified within the email headers, email sender fields, email CC fields, email BCC fields, email recipient fields, email subject fields, email bodies, email signatures, and/or email footers of the email resources  165 . In another embodiment, the email resources  165  may be associated with the client devices  120  if the email resources  165  are accessible to the client devices  120 , for instance, via one or more user identifiers, one or more device identifiers, and/or one or more device profiles associated with the client devices  120 . In yet another embodiment, the email resources  165  may be associated with the client devices  120  according to a listing of associated email resources  165  and client devices  120 . In any instance, the email resources  165  may include email messages, email attachments, and/or other electronic data, as described herein. 
     Next, in step  206 , the access control service  174  may identify one or more resource rules  171 . In certain embodiments, the access control service  174  may identify one or more resource rules  171  associated with one or more email resources  165 . In some embodiments, a given resource rule  171  may be associated with one or more email resources  165  and, similarly, a given email resource  165  may be associated with one or more resource rules  171 . In one embodiment, the resource rules  171  may be associated with the email resources  165  if the resource rules  171  are embedded within the email headers, email bodies, email signatures, and/or email footers of the email resources  165 . In particular, the email resources  165  may include embedded metadata and/or other instructions that represent one or more resource rules  171 . In another embodiment, the resource rules  171  may be associated with the email resources  165  if the resource rules  171  are affixed to the email resources  165 , such as attachments to the email resources  165 . In yet another embodiment, the resource rules  171  may be associated with the email resources  165  according to a listing of associated email resources  165  and resource rules  171 . In any instance, the resource rules  171  may regulate access to the email resources  165  associated with the resource rules  171  by the client devices  120  associated with the email resources  165 , as described herein. 
     Then, in step  209 , the access control service  174  may determine whether the email resources  165  satisfy the resource rules  171  associated with the email resources  165 . In certain embodiments, the access control service  174  may determine that the client devices  120  associated with the email resources  165  are authorized to access the email resources  165  if the email resources  165  satisfy the associated resources rules  171 . In any instance, the access control service  174  may determine whether the state of the email resources  165  satisfies the requirements specified by the associated resource rules  171 . In particular, the access control service  174  may determine whether the email headers, email sender fields, email CC fields, email BCC fields, email recipient fields, email subject fields, email bodies, email signatures, email footers, and/or email attachments of the email resources  165  satisfy the associated resource rules  171 , as described herein. 
     If the access control service  174  determines that the email resources  165  do not satisfy the resource rules  171 , then the access control service  174  may proceed to step  212  and may modify the email resources  165 . In certain embodiments, the access control service  174  may modify the email resources  165  so that the email resources  165  satisfy the resource rules  171  associated with the email resources  165 . In some embodiments, the access control service  174  may modify one or more portions of the email resources  165 . In other embodiments, the access control service  174  may modify all portions of and/or the entirety of the email resources  165 . In any instance, the access control service  174  may modify the email resources  165  by formatting, encoding, configuring, adding, removing, stripping, moving, replacing and/or flagging portions of the email resources  165 , as described herein. 
     On the contrary, if the access control service  174  determines that the email resources  165  satisfy the resource rules  171 , then the access control service  174  may proceed to step  215  and may authorize the client devices  120  to access the email resources  165 . In certain embodiments, the access control service  174  may authorize the client devices  120  to access the email resources  165  by transmitting the email resources  165  to one or more client side applications  126  executed by the client devices  120 . In some embodiments, the access control service  174  may authorize the client devices  120  to access the email resources  165  by notifying the client devices  120  that the email resources  165  may be downloaded from the access control service  174  and may further transmit the email resources  165  to the client devices  120  upon a request  177 . In any instance, the access control service  174  may authorize the client devices  120  to access the email resources  165  by providing the client devices  120  with a means of accessing the email resources  165 . In one embodiment, the access control service  174  may authorize the client devices  120  to access one or more unmodified email resources  165 . In another embodiment, the access control service  174  may authorize the client devices  120  to access one or more email resources  165  that have been modified by the access control service  174  so that the email resources  165  satisfy the resource rules  171  associated with the email resources  165 . 
       FIG. 3  is a flowchart illustrating exemplary functionality performed by a client side application  126  executed by a client device  120  ( FIG. 1 ) according to certain embodiments. It is understood that the flowchart of  FIG. 3  provides merely an example of the many different types of functional arrangements that may be employed to implement the operation of the client side application  126  as described herein. As an alternative, the flowchart of  FIG. 3  may be viewed as depicting an example of steps of a method implemented in the client device  120  according to one or more embodiments. 
     Beginning with step  303 , the client side application  126  may transmit one or more requests  177  to access one or more email resources  165 . In certain embodiments, the client side application  126  may transmit requests  177  to an access control service  174 . In some embodiments, the requests  177  may include a listing of specific email resources  165  that the client device  120  seeks to access. In other embodiments, the requests  177  may include an indication that the client device  120  seeks access to email resources  165  associated with the client device  120 , such as email resources  165  addressed to the user of the client device  120 . In any instance, the requests  177  may include data from the data store  122  of the client device  120 , such as device profiles  123 , user identifiers  132 , and device identifiers  135  associated with the client device  120 , as described herein. 
     Next, in step  306 , the client side application  126  may receive one or more email resources  165 . In certain embodiments, the client side application  126  may receive one or more email resources  165  from an access control service  174  executed by an access control server  150 . In one embodiment, the client side application  126  may directly receive the email resources  165  from the access control service  174 . In another embodiment, the client side application  126  may receive one or more indications from the access control service  174  that specify that the email resources  165  are available for download from the access control service  174 . In such embodiment, the client side application  126  may request to download the email resources  165  from the access control service  174  in response to receiving an indication that the email resources  165  are available for download from the access control service  174 . In some embodiments, the client side application  126  may receive one or more email resources  165  from an enterprise email service, such as Microsoft Exchange or Lotus Notes, or from a distribution service executed by a distribution server, as described herein. 
     Then, in step  309 , the client side application  126  may identify one or more resource rules  171 . In certain embodiments, the client side application  126  may identify one or more resource rules  171  associated with one or more email resources  165 . In some embodiments, the resource rules  171  may be associated with multiple email resources  165  and the email resources  165  may be associated with multiple resource rules  171 , as described herein. In one embodiment, the resource rules  171  may be associated with the email resources  165  if the resource rules  171  are embedded within the email headers, email bodies, email signatures, and/or email footers of the email resources  165 . In particular, the email resources  165  may include embedded metadata and/or other instructions that represent one or more resource rules  171 . In another embodiment, the resource rules  171  may be associated with the email resources  165  if the resource rules  171  are affixed to the email resources  165 , such as attachments to the email resources  165 . In yet another embodiment, the resource rules  171  may be associated with the email resources  165  according to a listing of associated email resources  165  and resource rules  171 . In any instance, the resource rules  171  may regulate access to the email resources  165  associated with the resource rules  171  by the client devices  120  associated with the email resources  165 , as described herein. 
     Next, in step  312 , the client side application  126  may determine whether the email resources  165  satisfy the resource rules  171  associated with the email resources  165 . In certain embodiments, the client side application  126  may determine that the client device  120  associated with the email resources  165  is authorized to access the email resources  165  if the email resources  165  satisfy the associated resources rules  171 . In any instance, the client side application  126  may determine whether the state of the email resources  165  satisfies the requirements specified by the associated resource rules  171 . In particular, the client side application  126  may determine whether the email headers, email sender fields, email CC fields, email BCC fields, email recipient fields, email subject fields, email bodies, email signatures, email footers, and/or email attachments of the email resources  165  satisfy the associated resource rules  171 , as described herein. 
     If the client side application  126  determines that the email resources  165  do not satisfy the resource rules  171 , then the client side application  126  may proceed to step  315  and may modify the email resources  165 . In certain embodiments, the client side application  126  may modify the email resources  165  so that the email resources  165  satisfy the resource rules  171  associated with the email resources  165 . In some embodiments, the client side application  126  may modify one or more portions of the email resources  165 . In other embodiments, the access control service  174  may modify all portions of and/or the entirety of the email resources  165 . In any instance, the client side application  126  may modify the email resources  165  by formatting, encoding, configuring, adding, removing, stripping, moving, replacing and/or flagging portions of the email resources  165 , as described herein. 
     On the contrary, if the client side application  126  determines that the email resources  165  satisfy the resource rules  171 , then the client side application  126  may proceed to step  318  and may authorize the client device  120  to access the email resources  165 . In certain embodiments, the client side application  126  may authorize the client device  120  to access the email resources  165  by providing the client devices  120  with a means of accessing the email resources  165 . For example, the client side application  126  may enable storing, installing, activating, rendering and/or executing the email resources  165  on the client device  120 , as described herein. In one embodiment, the client side application  126  may authorize the client device  120  to access one or more unmodified email resources  165 . In another embodiment, the client side application  126  may authorize the client device  120  to access one or more email resources  165  that have been modified by the access control service  174  so that the email resources  165  satisfy the resource rules  171  associated with the email resources  165 . In yet another embodiment, the client side application  126  may authorize the client device  120  to access one or more email resources  165  that have been modified by the client side application  126  so that the email resources  165  satisfy the resource rules  171  associated with the email resources  165 . 
       FIG. 4  is an example of a user interface  137   a  that allows an administrator of an access control service  174  ( FIG. 1 ) to associate one or more resource rules  171  ( FIG. 1 ) with one or more email resources  165  ( FIG. 1 ). In certain embodiments, the user interface  137   a  may include a grouping view field  402 , a rules view field  404 , an add rules button  406 , one or more rules description fields  408 , one or more action buttons  410 , and one or more defined rules  412 . 
     The grouping view field  402  may allow the administrator to select a group of client devices  120  and/or a group of users of client devices  120  to manage. For example, the administrator may manipulate the resource rules  171  that apply to the “Enterprise” group of client devices  120  by selecting the “Enterprise” grouping from the pull-down provided by the grouping view field  402 . The rules view field  404  may allow the administrator to filter the resource rules  171  to manage. For instance, the administrator may filter the resource rules  171  by either selecting the “All Email Rules” set of resource rules  171  or the “Active Email Rules” set of resource rules  171  from the options provided by the rules view field  404 . 
     The add rules button  406  may allow the administrator to add new resource rules  171  to the collection of resource rules  171  that apply to the “Enterprise” group of client devices  120 . For example, invoking the add rules button  406  may instruct the access control service  174  to provide another user interface  137  in which the administrator may define one or more new resource rules  171 , as will be described in  FIG. 5 . The rules description fields  408  may specify one or more characteristics that describe each of the resource rules  171 . For instance, the rules description fields  408  may include indications of whether a rule is active  408   a , a name of a rule  408   b , a storage location of a rule  408   c , a brief description of a rule  408   d , an assignment of a rule  408   e , an effective date and/or expiration date of a rule  408   f , and a last modified date of a rule  408   g . The action buttons  410  may allow an administrator to take one or more actions to a resource rule  171 , such as editing the resource rule  171  and/or adjusting the settings of a resource rule  171 . The defined rules  412  may include one or more resource rules  171  that have been previously created by an administrator of the access control service  174 , such as the “Encrypt Email Attachments” rule  412   a  and the “Remove Email Attachments” rule  412   b.    
       FIG. 5  is an example of a user interface  137   b  that allows an administrator of an access control service  174  ( FIG. 1 ) to create one or more new resource rules  171  ( FIG. 1 ), which may provide and/or control access to one or more applications and/or services accessible to one or more client devices  120  ( FIG. 1 ). In certain embodiments, the user interface  137   b  may include a rule type field  502 , an access credentials field  504 , an access rights field  506 , and one or more action buttons  508 . In some embodiments, the access rights field  506  may include an “Encrypt All Attachments” button  506   a  and a “Remove All Attachments” button  506   b.    
     The rule type field  502  may include one of more types of resource rules  171  that may be created through the user interface  137   b . For example, an administrator of the access control service  174  may select “Exchange ActiveSync” from the rules type field  502  to create resource rules  171  associated with email resources  165  ( FIG. 1 ). The access credentials field  504  may include one or more fields that accept input of one or more credentials for access to one or more applications and/or services accessible to the client devices  120 . For instance, an administrator of the access control service  174  may input the “Domain,” “Username,” “Email Address,” “Password,” and “Payload Certificates” associated with the client devices  120 . The access rights field  506  may include one or more access rights that may be defined for the client devices  120 , which may control access by client devices  120  to applications and/or services. For example, an administrator of the access control service  174  may apply one or more access restrictions including “Prevent Moving Messages,” “Prevent Use in 3 rd  Party Apps,” “Disable recent contact sync,” “Encrypt All Attachments”  506   a , and “Remove All Attachments”  506   b . The action buttons  508  may include one or more buttons that save and/or delete the resource rules  171  defined in the user interface  137   b . For example, an administrator of the access control service  174  may invoke the “Save” action button  508  to store the resource rules  171  associated with the email resources  165  in the data store  153  ( FIG. 1 ) of the access control server  150  ( FIG. 1 ). 
       FIG. 6  is an example of a user interface  137   c  executed by a client side application  126  ( FIG. 1 ) on a client device  120  ( FIG. 1 ). In certain embodiments, the client side application  126  may be an application native to the client device  120  that is capable of receiving and/or rendering email resources  165 . For example, the client side application  126  may be a native email application, such as Microsoft Outlook or Apple Mail. The client side application  126  may include an email selection field  602  and an email viewing pane  604 . The email selection field  602  may include one or more email messages that may be selected to access within the email viewing pane  604 . For example, the user of the client device, such as “John Smith,” may select an email message entitled “Confidential Q3 2012 Revenue” sent to “John Smith” from “George Williams.” The email viewing pane  604  may include a sender field, a recipient field, a title field, a body field, and one or more attachments  606 . For instance, the email viewing pane  604  may provide a user of a client device  120  to access the attachment entitled “PROTECTED: Q3 2012 Revenue.pdf.” 
       FIG. 7  is an example of a user interface  137   d  executed by a client side application  126  ( FIG. 1 ) on a client device  120  ( FIG. 1 ). In certain embodiments, the client side application  126  may be an application native to the client device  120  that is capable of receiving and/or rendering email resources  165 . For example, the client side application  126  may be a native email application, such as Microsoft Outlook or Apple Mail, as similarly described in  FIG. 6 . In some embodiments, the user of the client device  120  may request to access the attachment entitled “PROTECTED: 03 2012 Revenue.pdf” by selecting the attachment on the user interface  137   d . In one embodiment, the attachment entitled “PROTECTED: Q3 2012 Revenue.pdf” may be associated with resource rules  171  ( FIG. 1 ) that specify that the email resources  165  may only be accessed via a secure container application. 
     The user interface  137   d  may provide an access selection field  702  to provide the user of the client device  120  with one or more access applications and/or services that are available for accessing the email resources  165  in accordance with the associated resource rules  171 . For example, the access selection field  702  may specify that a client side application  126  with secure container capabilities may be selected, a client side application  126  with native email capabilities may not be selected, and a printing function of the client device  120  may not be selected. By selecting the client side application  126  with secure container capabilities from the access selection field  702 , the current client side application  126  with native email capabilities may call on the client side application  126  with secure container capabilities in order to access the email attachment. 
       FIG. 8  is an example of a user interface  137   e  executed by a client side application  126  ( FIG. 1 ) on a client device  120  ( FIG. 1 ). In certain embodiments, the client side application  126  may be a secure container application that is capable of receiving and/or rendering email resources  165 , as described herein. In some embodiments, the user interface  137   e  may provide an authentication form which must be filled out by the user of the client device  120  in order to gain access to one or more email resources  165  accessible through the secure container environment of the client side application  126 . In particular, the user interface  137   e  may provide an authentication form that includes a username field  802 , a password field  804 , and a login button  806 . A user of the client device  120 , such as “John Smith,” may provide a username, such as “John Smith,” in the username field  802 , may provide a password, such as “,” and may invoke the login button  806  to provide the access credentials to the client side application  126 . Responsive to a determination that the access credentials provided by the user of the client device  120  are authorized, the client side application  126  may provide the user of the client device  120  with access to the secure container environment of the client side application  126 . 
       FIG. 9  is an example of a user interface  137   f  executed by a client side application  126  ( FIG. 1 ) on a client device  120  ( FIG. 1 ). In certain embodiments, the client side application  126  may be a secure container application that is capable of receiving and/or rendering email resources  165 , as described herein. The secure container environment of the client side application  126  may include a views pane  902 , a categories pane  904 , and action buttons  906 . The views pane  902  may include one or more views that are accessible to the user of the client device  120 , such as an “all content” view, a “new content” view, a “recent activity” view, and a “favorites” view. The user of the client device  120  may select one of the available views, each of which may include a subset of email resources  165  related to the certain view. The categories pane  904  may include one or more categories of email resources  165  that are available to the user of the client device  120 , such as an “Email Attachments” category that is a subset of an “Email Resources” category. The user of the client device  120  may, for instance, select the “Email Attachments” category to access one or more email attachments that are configured to be accessible via the secure container environment of the client side application  126 . The action buttons  906  may include a “Content” button, a “Downloads” button, a “Search” button, an “Updates” button, and a “Settings” button that may launch other user interfaces  137  provided by the client side application  126  to enable additional views, applications, and/or services. 
       FIG. 10  is an example of a user interface  137   e  executed by a client side application  126  ( FIG. 1 ) on a client device  120  ( FIG. 1 ). In certain embodiments, the client side application  126  may be a secure container application that is capable of receiving and/or rendering email resources  165 , as described herein. The secure container environment of the client side application  126  may include an accessible resource listing  1002  and an access notification  1004 . The user of the client device  120  may select an email resource  165 , such an as email attachment, from the accessible resource listing  1002 . Responsive to the user of the client device  120  selecting the “Q3 2012 Revenue.pdf” email resource  165  from the accessible resource listing  1002 , the client side application  126  may provide the user with access to the email resource  165  by unlocking the protected file. In particular, the email resource  165  may have been encrypted with a symmetric cryptographic key and/or a asymmetric cryptographic key by an access control service  174  ( FIG. 1 ) according to one or more resource rules  171  ( FIG. 1 ) associated with the email resource  165 , as described herein. Consequently, the client side application  126  may decrypt the email resource  165  to enable access to the email resource  165  and may provide an access notification  1004  that specifies that the client side application  126  is “Unlocking (the) PROTECTED file” and to “Please Wait” to access the email resource  165  while the client side application  126  unlocks the email resource  165 . 
       FIG. 11  is an example of a user interface  137   e  executed by a client side application  126  ( FIG. 1 ) on a client device  120  ( FIG. 1 ). In certain embodiments, the client side application  126  may be a secure container application that is capable of receiving and/or rendering email resources  165 , as described herein. The client side application  126  may include a resource title pane  1102 , a resource content pane  1104  and a resource page selection pane  1106 . The resource title pane  1102  may specify the title of the email resources  165 , such as “Q3 2012 Revenue.” The resource content pane  1104  may include the body of the email resources  165 , such as the pages of the PDF file “Q3 2012 Revenue.” The resource page selection pane  1106  may include one or more pages of the email resources  165 . The user of the client device  120  may, for example, select a page from the resource page selection pane  1106 . Responsive to the user of the client device  120  selecting a certain page from the resource page selection pane  1106 , the client side application  126  may navigate to the selected page and present the content of the selected page in the resource content pane  1104 . 
       FIG. 12  depicts certain illustrative components for a networked environment  1200  according to various embodiments. In certain embodiments, the networked environment  1200  may include one or more networks  110 , one or more client devices  120 , an access control service  174 , and one or more email services  1202 . The email services  1202  may be configured to provide the client devices  120  with access to one or more email resources  165  ( FIG. 1 ) associated with the email services  1202 . As an example, the email services  1202  may be and/or include one or more enterprise email services, such as Microsoft Exchange, Lotus Notes, and/or other services capable of distributing email resources  165  to client devices  120 . The access control service  174  may be configured to authorize the client devices  120  to access to the email services  1202 , may control the manner in which the client devices  120  are authorized to access the email services  1202 , and may provide the client devices  120  with access to the email services  1202 . 
     In one embodiment, the access control service  174  may be configured to proxy email resources  165  provided to the client devices  120  by the email services  1202 . The access control service  174  may, for instance, filter all email resources  165  transmitted between the email services  1202  and the client devices  120 . Alternatively, the access control service  174  may proxy email resources  165  in transit to the client devices  120  from the email services  1202 . In another embodiment, the access control service  174  may be configured to provide a gateway for access to the email services  1202 . The access control service  174  may, for instance, provide authorized client devices  120  with access to the email services  1202  and deny unauthorized client devices  120  from accessing the email services  1202 . 
     In any instance, the access control service  174  may be configured to determine whether the client devices  120  reauthorized to access the email resources  165 . The access control service  174  may, for example, receive one or more requests  177  ( FIG. 1 ) to access the email services  1202  from the client devices  120 . The access control service  174  may determine whether the client devices  120  associated with the requests  177  are authorized to access the email services  1202  based on, for instance, one or more device profiles  123  ( FIG. 1 ), one or more user identifiers  132  ( FIG. 1 ), one or more device identifiers  135  ( FIG. 1 ) associated with the client device  120 , which may be included in the requests  177 . The access control service  174  may provide the client devices  120  with access to the email services  1202  in response to a determination that the client devices  120  are authorized to access the email services  1202 . In one embodiment, the access control service  174  may establish a communicative connection between the email services  1202  and the client devices  120 , which may facilitate the transmission of email resources  165  between the email services  1202  and the client devices  120 . In another embodiment, the access control service  174  may establish a communicative connection between the access control service  174  and the client devices  120 , which may facilitate the transmission of email resources  165  associated with the email service  1202  between the access control service  174  and the client devices  120 . 
     Additionally, the access control service  174  may be configured to control access to the email resources  165  by the client devices  120 . The access control service  174  may determine which email resources  165  the client devices  120  are authorized to access. The access control service  174  may also modify the email resources  165  before providing the client devices  120  with access to the email resources  165 . In one embodiment, the access control service  174  may strip and/or remove one or more email attachments from the email resources  165 . In another embodiment, the access control service  174  may configure one or more email attachments to be exclusively accessible via one or more client side applications  126  ( FIG. 1 ) on the client devices  120 . For example, the access control service  174  may transmit one or more cryptographic keys that may decode one or more encoded portions of the email resources  165  to the client side applications  126  on the client devices  120 . In another embodiment, the access control service  174  may encode one or more email attachments to the email resources  165  before making the email attachments accessible to the client devices  120 . In yet a further embodiment, the access control service  174  may instruct the email services  1202  to strip and/or remove one or more email attachments from the email resources  165 , encode the email attachments based at least in part on one or more cryptographic keys, and configure the email attachments to be exclusively accessible via one or more client side applications  126  on the client devices  120 . 
     Furthermore, the access control service  174  may be configured to provide the client devices  120  with access to the email services  1202  and/or the email resources  165  associated with the email services  1202 . In one embodiment, the access control service  174  may be configured to transmit email resources  165  to the client devices  120 . For example, the access control service  174  may establish a secure communicative connection with the client devices  120 , such as HTTPS/SSL, through which the access control service  174  may transmit the email resources  165  associated with the email services  1202  to the client devices  120 . In another embodiment, the access control service  174  may be configured to transmit instructions to the email services  1202  that specify that the email services  1202  should transmit the email resources  165  to the client devices  120 . 
       FIG. 13  is a flowchart illustrating exemplary functionality performed by an access control service  174  executed by an access control server  150  ( FIG. 1 ) according to certain embodiments. It is understood that the flowchart of  FIG. 13  provides merely an example of the many different types of functional arrangements that may be employed to implement the operation of the access control service  174  as described herein. As an alternative, the flowchart of  FIG. 13  may be viewed as depicting an example of steps of a method implemented in the access control server  150  according to one or more embodiments. 
     Beginning with step  1302 , an access control service  174  may proxy one or more email resources  165  ( FIG. 1 ) in transit to one or more client devices  120  ( FIG. 1 ) from one or more email services  1202  ( FIG. 12 ). In one embodiment, the access control service  174  may be configured to proxy all data transmitted between the email services  1202  and the client devices  120 . For example, the access control service  174  may identify the email resources  165  in transit to the client devices  120  via the access control service  174  and may prohibit the email resources  165  from proceeding to the client devices  120  as transmitted by the email services  1202 . In another embodiment, the access control service  174  may be configured to act as a gateway that controls access to the email services  1202 . For instance, the access control service  174  may transmit instructions to the email services  1202  that specify that email resources  165  intended for the client devices  120  must be transmitted to the client devices  120  via the access control service  174 . 
     Next, in step  1304 , the access control service  174  may remove one or more email attachments from the email resources  165 . In certain embodiments, one or more resource rules  171  ( FIG. 1 ) may specify that all email attachments to the email resources  165  must be stripped and/or removed from the email resources  165  before the client devices  120  are provided with access to the email resources  165 . In one embodiment, the access control service  174  may be configured to copy the email attachments from the email resources  165  and delete the original email attachments from the email resources  165 . In another embodiment, the access control service  174  may be configured to store the removed email attachments. For instance, the access control service  174  may store the removed email attachments in the data store  153  ( FIG. 1 ) of the access control server  150 . 
     Then, in step  1306 , the access control service  174  may encode the email attachments based at least in part on one or more cryptographic keys. In certain embodiments, one or more resource rules  171  may specify that email attachments to the email resources  165  must be encoded based at least in part on the cryptographic keys before the client devices  120  are provided with access to the email resources  165 . In some embodiments, the resource rules  171  may specify a required and/or permitted cryptographic key length for the cryptographic key used to encode the email attachments. In one embodiment, the access control service  174  may encode the email attachments with the advanced encryption standard (AES) algorithm. In another embodiment, the access control service  174  may encode the email attachments with the data encryption standard (DES) algorithm. In any instance, the access control service  174  may encode the email attachments in manner which protects the email attachments from being intercepted and accessed by obfuscating the data of the email attachments based at least in part on the cryptographic keys. 
     Furthermore, in step  1308 , the access control service  174  may authorize the client devices  120  to access the email resources  165 . In one embodiment, the access control service  174  may be configured to transmit one or more email resources  165  to the client devices  120 . For example, the access control service  174  may transmit the email resources  165  with removed email attachments to the client devices  120 . In another embodiment, the access control service  174  may be configured to transmit the removed email attachments to the client devices  120 . For instance, the access control service  174  may transmit email attachments stored in one or more data stores  153  of the access control server  150  to the client devices  120 . In yet another embodiment, the access control service  174  may be configured to transmit one or more encoded email attachments and the associated cryptographic keys to one or more client side application  126  of the client devices  120 . In yet a further embodiment, the access control service  174  may be configured to transmit instructions to the email services  1202  that specify that the email resources  165 , the removed email attachments, and/or the encoded email attachments should be transmitted to the client devices  120 . 
       FIG. 14  depicts certain illustrative components for a networked environment  1400  according to various embodiments. In certain embodiments, the networked environment  100  may include one or more networks  110 , one or more client devices  120 , an access control service  174 , and one or more email services  1202 . The networked environment  1400  may be similar to the networked environment  1200  in  FIG. 12 . While the networked environment  1200  may include the same components as the networked environment  1400 , the organization of the components of the two networked environment may differ. In particular, the email services  1202  in the networked environment  1400  may communicate directly with the client devices  120 , whereas the access control service  174  in the networked environment  1200  must relay all communications between the email services  1202  and client devices  120 . The access control service  174  of the networked environment  1400  may be configured to determine which email resources  165  associated with the email services  1202  may be accessed by the client devices  120 , control the manner in which the client devices  120  are authorized to access the email resources  165 , and may provide the client devices  120  with access to the email resources  165 . 
     In certain embodiments, the access control service  174  may determine which email resources  165  associated with the email services  1202  may be accessed by the client devices  120  by configuring the email services  1202 . In some embodiments, the access control service  174  may transmit one or more instructions to the email services  1202  that configure the functionality of the email services  1202 . As an example, the access control service  174  may utilize an instruction protocol, such as Microsoft PowerShell, to transmit the instructions to an email service  1202 , such as Microsoft Exchange. In one embodiment, the instructions may represent and/or specify one or more resource rules  171  ( FIG. 1 ) that must be satisfied in order to provide the client devices  120  with access to the email resources  165 . The resource rules  171  may, for example, specify that all email attachments to the email resources  165  must be removed from the email resources  165  before the email resources  165  may be provided to the client devices  120 . The resource rules  171  may further specify that the removed email attachments must be transmitted to the access control service  174 . 
     Additionally, in certain embodiments, the access control service  174  may control the manner in which the client devices  120  are authorized to access the email resources  165  by configuring the email resources  165  before they are provided to the client devices  120 . In some embodiments, the access control service  174  may configure one or more email attachments removed and/or stripped from one or more email resources  165 , which may have been transmitted to the access control service  174  by the email services  1202 . In one embodiment, the access control service  174  may configure the email attachments by modifying the email attachments according to one or more resource rules  171 . The resource rules  171  may, for example, specify that the email attachments must be encoded based at least in part on one or more cryptographic keys before the email attachments are provided to the client devices  120 . The resource rules  171  may further specify that the email attachments must be configured to be exclusively accessible via one or more client side applications  126  on the client devices  120  before the email attachments are provided to the client devices  120 . 
     Furthermore, in certain embodiments, the access control service  174  may provide the client devices  120  with access to the email resources  165  by authorizing the client devices for access to the email resources  165 . In some embodiments, the access control service  174  may tailor the authorization of the client devices  120  in accordance with one or more resource rules  171 . For instance, the resource rules  171  may specify that the email resources  165  may only be transmitted to the client devices  120  over a secure connection, such as over an HTTPS/SSL connection. In one embodiment, the access control service  174  may transmit instructions to the email services  1202  that specify that the email services  1202  may transmit email resources  165  with removed email attachments to the client devices  120 . In another embodiment, the access control service  174  may transmit the email attachments, which have been removed from the email resources  165  by the email services  1202 , encoded based at least in part on one or more cryptographic keys by the access control service  174 , and configured to be exclusively accessible via one or more client side applications  126  on the client devices  120 , to the client devices  120 . In yet another embodiment, the access control service  174  may transmit one or more cryptographic keys capable of decoding the encoded email attachments to one or more client side applications  126  on the client devices  120 . 
       FIG. 15  is a flowchart illustrating exemplary functionality performed by an access control service  174  executed by an access control server  150  ( FIG. 1 ) according to certain embodiments. It is understood that the flowchart of  FIG. 15  provides merely an example of the many different types of functional arrangements that may be employed to implement the operation of the access control service  174  as described herein. As an alternative, the flowchart of  FIG. 15  may be viewed as depicting an example of steps of a method implemented in the access control server  150  according to one or more embodiments. 
     Beginning with step  1502 , the access control service  174  may identify one or more email resources  165  ( FIG. 1 ) that are associated with one or more client devices  120  ( FIG. 1 ). In certain embodiments, the access control service  174  may identify the email resources  165  by receiving the email resources  165  from an email service  1202  associated with the email resources  165 . For example, the access control service  174  may receive the email resources  165  from a Microsoft Exchange email service. In one embodiment, the access control service  174  may proxy email resources  165  in transit to the client devices  120  from one or more email services  1202  ( FIG. 14 ). For example, the access control service  174  may proxy email resources  165  transmitted between the email service  1202  and the client devices  120  and may filter certain email resources  165 . In another embodiment, the access control service  174  may transmit instructions to the email services  1202  that specify that the email resources  165  must be transmitted to the access control service  174 , rather than the client devices  120 . In yet another embodiment, the access control service  174  may transmit instructions to the email services  1202  that specify one or more resource rules  171  ( FIG. 1 ) that must be satisfied in order for the client devices  120  to be authorized to access the email resources  165 . For example, the access control service  174  may instruct the email services  1202  that email attachments to the email resources  165  must be removed from the email resources  165  and the access control service  174  may subsequently fetch then email attachments, in accordance with the resource rules  171 . 
     Next, in step  1504 , the access control service  174  may modify one or more portions of the email resources  165 . In certain embodiments, the access control service  174  may modify portions of email resources  165  received from an email service  1202 . In some embodiments, the access control service  174  may modify portions of the email resources  165  in accordance with one or more resource rules  171  that must be satisfied for the client devices  120  to be authorized to access the email resources  165 . In one embodiment, the access control service  174  may remove and/or strip one or more email attachments to the email resources  165  from the email resources  165 . In another embodiment, the access control service  174  may encode one or more email attachments to the email resources  165  based at least in part on one or more cryptographic keys. 
     Then, in step  1506 , the access control service  174  may authorize the client devices  120  to access the email resources  165 . In certain embodiments, the access control service  174  may be configured to transmit the email resources  165  to the client devices  120 . In one embodiment, the access control service  174  may transmit email resources  165  with removed email attachments to the client devices  120 . In another embodiment, the access control service  174  may transmit the email attachments removed from the email resources  165  to the client devices  120 . In yet another embodiment, the access control service  174  may transmit one or more encoded email attachments and the associated cryptographic keys to one or more client side applications  126  on the client devices  120 . In yet a further embodiment, the access control service  174  may transmit instructions to the email services  1202  that specify that the email resources  165 , the removed email attachments, and/or the encoded email attachments should be transmitted to the client devices  120 . 
       FIG. 16  is a flowchart illustrating exemplary functionality performed by one or more client side applications  126  executed by one or more client devices  120  ( FIG. 1 ) according to certain embodiments. It is understood that the flowchart of  FIG. 16  provides merely an example of the many different types of functional arrangements that may be employed to implement the operation of the client side application  126  as described herein. As an alternative, the flowchart of  FIG. 16  may be viewed as depicting an example of steps of a method implemented in the client device  120  according to one or more embodiments. 
     Beginning with step  1602 , a client device  120  identifies one or more encoded email resources  165  ( FIG. 1 ). In certain embodiments, the client device  120  may identify encoded email resources  165  by querying one or more data stores  122  ( FIG. 1 ) of the client device  120  to determine whether the data stores  122  hold encoded email resources  165 . In some embodiments, the client device  120  may identify encoded email resources  165  by receiving the encoded email resources  165  on the client device  120 . In one embodiment, the client device  120  may receive the encoded email resources  165  on the client device  120  from one or more email services  1202  ( FIGS. 12 and 14 ). In another embodiment, the client device  120  may receive the encoded email resources  165  on the client device  120  from an access control service  174 . 
     Next, in step  1604 , the client device  120  identifies one or more cryptographic keys associated with the encoded email resources  165 . In certain embodiments, the client device  120  may identify the cryptographic keys associated with the encoded email resources  165  by querying the data stores  122  of the client device  120  to determine whether the data stores  122  hold cryptographic keys associated with the encoded email resources  165 . In some embodiments, the client device  120  may identify cryptographic keys associated with the encoded email resources  165  by receiving the cryptographic keys associated with the encoded email resources  165  on the client device  120 . In one embodiment, the client device  120  may receive the cryptographic keys associated with the encoded email resources  165  from an access control service  174 . In another embodiment, the client device  120  may receive the cryptographic keys associated with the encoded email resources  165  from an email service  1202 . 
     Then, in step  1606 , the client device  120  decodes the encoded email resources  165  based at least in part on the cryptographic keys associated with the encoded email resources  165 . In certain embodiments, the client side applications  126  on the client device  120  may decode the encoded email resources  165  based at least in part on the cryptographic keys associated with the encoded email resources  165 . In some embodiments, the client side application  126  may render and/or present the decoded email resources  165  on a user interface  137  ( FIG. 1 ) executed on a display  136  ( FIG. 1 ) of the client device  120 . 
       FIG. 17  shows schematic block diagrams of an exemplary access control server  150  and an exemplary client device  120  according to an embodiment of the present disclosure. The access control server  150  includes at least one processor circuit, for example, having a processor  1703  and a memory  1706 , both of which are coupled to a local interface  1709 . To this end, the access control server  150  may comprise, for example, at least one server computer or like device. Similarly, the client device  120  includes at least one processor circuit, for example, having a processor  1753  and a memory  1756 , both of which are coupled to a local interface  1759 . Additionally, the client device  120  may be in data communication with a display  136  for rendering user interfaces  137  ( FIG. 1 ) and one or more other I/O devices  1763  for inputting and outputting data. To this end, the client device  120  may comprise, for example, at least one client computer or like device. 
     The following is a general discussion of the components of the access control server  150  and the client device  120 . The local interface  1709  and  1759  may comprise, for example, a data bus with an accompanying address/control bus or other bus structure as can be appreciated. Stored in the memory  1706  and  1756  are both data and several components that are executable by the processors  1703  and  1753 . In particular, with regard to the access control server  150 , stored in the memory  1706  and executable by the processor  1703  are an access control service  174  and potentially other applications. Additionally, with regard to the client device  120 , stored in the memory  1756  and executable by the processor  1753  are a client side application  126  and potentially other applications. Also stored in the memory  1706  and  1756  may be a data store  153  and  122  and other data. In addition, an operating system may be stored in the memory  1706  and  1756  and executable by the processor  1703  and  1753 . 
     It is to be understood that there may be other applications that are stored in the memory  1706  and  1756  and are executable by the processor  1703  and  1753  as can be appreciated. Where any component discussed herein is implemented in the form of software, any one of a number of programming languages may be employed such as, for example, C, C++, C #, Objective C, Java, JavaScript, Perl, PHP, Visual Basic, Python, Ruby, Delphi, Flash, or other programming languages. 
     A number of software components are stored in the memory  1706  and  1756  and are executable by the processor  1703  and  1753 . In this respect, the term “executable” means a program file that is in a form that can ultimately be run by the processor  1703  and  1753 . Examples of executable programs may be, for example, a compiled program that can be translated into machine code in a format that can be loaded into a random access portion of the memory  1706  and  1756  and run by the processor  1703  and  1753 , source code that may be expressed in proper format such as object code that is capable of being loaded into a random access portion of the memory  1706  and  1756  and executed by the processor  1703  and  1753 , or source code that may be interpreted by another executable program to generate instructions in a random access portion of the memory  1706  and  1756  to be executed by the processor  1703  and  1753 , etc. An executable program may be stored in any portion or component of the memory  1706  and  1756  including, for example, random access memory (RAM), read-only memory (ROM), hard drive, solid-state drive, USB flash drive, memory card, optical disc such as compact disc (CD) or digital versatile disc (DVD), floppy disk, magnetic tape, or other memory components. 
     The memory  1706  and  1756  are defined herein as including both volatile and nonvolatile memory and data storage components. Volatile components are those that do not retain data values upon loss of power. Nonvolatile components are those that retain data upon a loss of power. Thus, the memory  1706  and  1756  may comprise, for example, random access memory (RAM), read-only memory (ROM), hard disk drives, solid-state drives, USB flash drives, memory cards accessed via a memory card reader, floppy disks accessed via an associated floppy disk drive, optical discs accessed via an optical disc drive, magnetic tapes accessed via an appropriate tape drive, and/or other memory components, or a combination of any two or more of these memory components. In addition, the RAM may comprise, for example, static random access memory (SRAM), dynamic random access memory (DRAM), or magnetic random access memory (MRAM) and other such devices. The ROM may comprise, for example, a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or other like memory device. 
     Also, the processor  1703  and  1753  may represent multiple processors, and the memory  1706  and  1756  may represent multiple memories that operate in parallel processing circuits, respectively. In such a case, the local interface  1709  and  1759  may be an appropriate network  110  ( FIG. 1 ) that facilitates communication between any two of the multiple processors  1703  and  1753 , or between any two of the memory  1706  and  1756 , etc. The local interface  1709  and  1759  may comprise additional systems designed to coordinate this communication, including, for example, performing load balancing. The processor  1703  and  1753  may be of electrical or of some other available construction. 
     Although the access control service  174 , client side application  126 , and other various systems described herein may be embodied in software or code executed by general purpose hardware as discussed above, as an alternative the same may also be embodied in dedicated hardware or a combination of software/general purpose hardware and dedicated hardware. If embodied in dedicated hardware, each can be implemented as a circuit or state machine that employs any one of or a combination of a number of technologies. These technologies may include, but are not limited to, discrete logic circuits having logic gates for implementing various logic functions upon an application of one or more data signals, application specific integrated circuits having appropriate logic gates, or other components, etc. Such technologies are generally well known by those skilled in the art and, consequently, are not described in detail herein. 
     The flowcharts of  FIGS. 2, 3, 13 and 15  show certain functionality and operations performed by the access control service  174  and client side application  126 , respectively. If embodied in software, each box may represent a module, segment, or portion of code that comprises program instructions to implement the specified logical function(s). The program instructions may be embodied in the form of source code that comprises human-readable statements written in a programming language or machine code that comprises numerical instructions recognizable by a suitable execution system such as a processor  1703  and  1753  in a computer system or other system. The machine code may be converted from the source code, etc. If embodied in hardware, each block may represent a circuit or a number of interconnected circuits to implement the specified logical function(s). 
     Although the flowcharts of  FIGS. 2, 3, 13 and 15  show a specific order of execution, it is understood that the order of execution may differ from that which is depicted. For example, the order of execution of two or more steps may be scrambled relative to the order shown. Also, two or more blocks shown in succession in  FIGS. 2, 3, 13 and 15  may be executed concurrently or with partial concurrence. Further, in some embodiments, one or more of the steps shown in  FIGS. 2, 3, 13 and 15  may be skipped or omitted. In addition, any number of counters, state variables, warning semaphores, or messages might be added to the logical flow described herein, for purposes of enhanced utility, accounting, performance measurement, or providing troubleshooting aids, etc. It is understood that all such variations are within the scope of the present disclosure. 
     Also, any logic or application described herein, including the access control service  174  and the client side application  126 , that comprises software or code can be embodied in any non-transitory computer-readable medium for use by or in connection with an instruction execution system such as, for example, a processor  1703  and  1753  in a computer system or other system. In this sense, the logic may comprise, for example, statements including instructions and declarations that can be fetched from the computer-readable medium and executed by the instruction execution system. In the context of the present disclosure, a “computer-readable medium” can be any medium that can contain, store, or maintain the logic or application described herein for use by or in connection with the instruction execution system. The computer-readable medium can comprise any one of many physical media such as, for example, magnetic, optical, or semiconductor media. More specific examples of a suitable computer-readable medium would include, but are not limited to, magnetic tapes, magnetic floppy diskettes, magnetic hard drives, memory cards, solid-state drives, USB flash drives, or optical discs. Also, the computer-readable medium may be a random access memory (RAM) including, for example, static random access memory (SRAM) and dynamic random access memory (DRAM), or magnetic random access memory (MRAM). In addition, the computer-readable medium may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or other type of memory device. 
     It should be emphasized that the above-described embodiments of the present disclosure are merely possible examples of implementations set forth for a clear understanding of the principles of the disclosure. Many variations and modifications may be made to the above-described embodiment(s) without departing substantially from the spirit and principles of the disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.