Lesson 1: Introduction to Public Folders

Public folders are repositories for all kinds of information. They can contain regular e-mail messages as well as multimedia clips, text documents, spreadsheets, and other data. A variety of messaging applications, including Outlook 2000, Internet mail clients, newsreaders, and Web browsers, can access these folders. You can also use standard Win32 programs, such as Microsoft Windows Explorer or Microsoft Office applications. The Installable File System driver of Exchange 2000 Server (ExIFS) makes public folders as accessible as directories on a hard disk.

This lesson provides a brief overview of public folders, including an introduction to architecture and information on relationships between public folders and directory objects. The advantages of mail-enabled public folders are introduced.


At the end of this lesson, you will be able to:

  • Describe the features of public folders.
  • List the various parts of a public folder.
  • Send messages to and on behalf of a public folder.

Estimated time to complete this lesson: 60 minutes


Public Folder Considerations

Public folders are primarily managed using Exchange System Manager, but users may also use Outlook 2000, Internet clients, Web browsers, or Windows Explorer to create public folders and set permissions and other configuration options. A user who creates a public folder becomes the folder's owner, but additional owners can be defined. The owner can manage permissions and folder rules using Outlook 2000. Other configuration settings, such as public folder replication, can be controlled only using Exchange System Manager. Of course, you need Administrative permissions in your administrative group if you want to control configuration settings.

Public Folder Databases

The actual public folder repositories are maintained in public stores. Each store consists of an Exchange database, which holds items in Messaging Application Programming Interface (MAPI) format, and an Exchange streaming database for items in Internet-based formats. You can check the location of the databases in Exchange System Manager when displaying the desired public store's Database tab. As outlined in Chapter 14, "Managing Server Configuration," one or more storage groups and public stores may be created on a particular server. It is also possible to remove all public stores from a server to create dedicated mailbox servers. However, at least one server holding the default public store for the MAPI-based public folders tree must exist within an administrative group. You can read more about the maintenance of Exchange 2000 Server databases in Chapter 20, "Microsoft Exchange 2000 Server Maintenance and Troubleshooting."

Public Folder Referrals

By default, a newly created top-level public folder is not replicated to any other server. Replication requires an explicit administrative step, but replication is not always necessary because all users in your organization can theoretically have direct access. Within a routing group, users can always work with local public folders, but users from other routing groups cannot if public folder referrals are not allowed. Every Routing Group Connector (RGC) provides a Do Not Allow Public Folder Referrals check box, which you can select to prevent Outlook 2000 users from accessing public folder resources in remote routing groups. Referrals and their purposes are covered in Lesson 3.

Public Folder Replication

Public folder replication gives you the means to distribute multiple instances of a public folder to different Exchange 2000 servers and keep them synchronized. In addition, an InterOrg Replication utility is available, which allows you to replicate public folder instances between Exchange organizations. Multiple public folder instances can share the user load and increase fault tolerance through redundancy. Public folder replication is covered in Chapter 18, "Public Folder Replication."

Internet Publishing

By default, every user can access public folder resources in the context of their access permissions via HTTP and Web Distributed Authoring and Versioning (WebDAV). In Chapter 11, "Internet-Based Client Access," you used the Add Network Places Wizard in Windows Explorer to configure a connection to a public folder tree. HTTP and WebDAV support is a very interesting feature, particularly for Macintosh or Unix users who want to share information with Windows clients. In addition to the public folder itself, all items within a public folder can be accessed through a URL, which is dynamically generated. URLs are constructed using the path to the folder and the Subject line of the item. This is demonstrated in Exercise 2 of Chapter 22, "Microsoft Outlook Web Access."

You can map public folders to Internet newsgroups and provide access to these forums through Network News Transfer Protocol (NNTP)-based newsreader clients. Likewise, push and pull feeds may be used to replicate public folder content with the USENET. The management of NNTP virtual servers and public folder newsgroups is covered in Chapter 11, "Internet-Based Client Access."

Full-Text Indexing

The Information Store service of Exchange 2000 Server is integrated with the Microsoft Search service of Microsoft Windows 2000 Server. This allows you to index the content of public folders and provide Outlook 2000 users with the ability to locate Microsoft Office documents and message attachments through full-text searches. Exchange 2000 Server is a very attractive document management platform, as explained in Chapter 14, "Managing Server Configuration."

Elements of a Public Folder

Public folder access relies on two elements: the public folder hierarchy and the public folder content (see Figure 17.1). The hierarchy shows a public folder within a public folder tree. The content consists of the actual items (such as messages and attachments, contact objects, or documents) stored in the public folder.

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Figure 17.1 The elements of a public folder in the Information Store

Public Folder Hierarchy

A public folder hierarchy develops when multiple folders are created. Top-level folders contain subfolders, and those can contain other subfolders. By navigating through the public folder tree, users can locate discussion forums and other information repositories conveniently. Exchange 2000 Server supports multiple public folder trees, also known as public folder hierarchies, which give you better administrative control and flexibility over workgroup and workflow solutions.

Hierarchy and Public Stores

Per server, each public folder tree must be associated with a separate public store. Public stores on different servers may refer to the same hierarchy, in which case the hierarchy is automatically replicated between them. Dedicated mailbox servers (servers without a public store) do not maintain any public folder tree information.

Exchange System Manager does not provide control over the time interval of the hierarchy replication. By default, hierarchy replication generates an e-mail message 60 seconds after the last modification has occurred. Replication messages are addressed to all those servers that maintain a public store associated with the affected hierarchy.

Public Folder Hierarchies and MAPI-Based Clients

The default MAPI-based hierarchy is created automatically on each server during setup. Because the default public store of each server is associated with the MAPI-based hierarchy, this hierarchy is replicated to all servers across the organization. Therefore, every user can examine the list of existing folders, even though the content might not be accessible (see Figure 17.2). In Outlook 2000 you can display the MAPI-based folder hierarchy (that is, Public Folders\All Public Folders) by selecting the Folder List command, which can be reached from the View menu. Only one MAPI-based hierarchy can exist per server.

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Figure 17.2 Accessing public folder content on a different server

The following are the two types of folder hierarchies supported by Exchange 2000 Server:

  • Default (MAPI clients). MAPI-based clients, as well as Web browsers, and Windows applications, such as Microsoft Word, Microsoft Excel, or Windows Explorer, can access this hierarchy.
  • Alternate (general purpose). Web browsers and Windows applications, such as Microsoft Word, Microsoft Excel, or Windows Explorer, can access this hierarchy, but MAPI-based clients are unable to display these public folder trees.

NOTE


Exchange System Manager allows you to create multiple hierarchies. However, Outlook 2000 is only able to access the default MAPI-based public folder tree. Microsoft plans to provide support for alternate public folder trees in future versions of Outlook.

Public Folder Contents

The public folder contents are the actual items in a public folder. To work with the contents, you must open the folder by selecting it in the client's folder pane and displaying the items in the right pane, also called the details pane. When you open a public folder, your client program will send an open request to your home server. If the server has the contents, you will get access. If the home server doesn't have the contents, it returns a referral list to the client. Based on the information from this list, the client will connect to a server within the local routing group or in a remote routing group. If all target servers are inaccessible for some reason, you will receive an error message that the folder content could not be located. You can read more about public folder access in Lesson 3.

It doesn't matter to the user where the data is stored as long as Outlook 2000 has access to the contents. The amount of data that needs to be transferred between networks can be decreased, however, if the content of a public folder is available locally. For this reason, you should consider multiple replicas if public folder usage creates a significant amount of inter-network traffic. There is, however, a trade-off: Replication itself creates network traffic, and the replicated content consumes hard disk space. Public folder replication is covered in depth in Chapter 18, "Public Folder Replication."

Public Folders Within the Active Directory Directory Service

By default, public folders are not mail-enabled, meaning they do not possess e-mail addresses. To mail-enable a public folder, launch Exchange System Manager, expand the corresponding public folder hierarchy, such as the MAPI-based Public Folders, right-click the desired public folder, point to All Tasks, and select the Mail Enable command. To verify the results, display the public folder's properties afterwards. You will find e-mail-related property sheets (Exchange General, E-Mail Addresses, Exchange Advanced, and Member Of) in addition to the standard tabs (General, Replication, Limits, Details, and Permissions). Switch to E-Mail Addresses and check for assigned address information. It may take a little while for the Recipient Update Service to generate the e-mail addresses, but you can accelerate this process, as explained in Chapter 13, "Creating and Managing Recipients."

NOTE


Mail-enabling a public folder does not affect existing or new subfolders. These folders do not inherit the mail-enabled state. To mail-enable an entire public folder sub-tree, prepare the top-level folder first, then right-click on it in Exchange System Manager, point to All Tasks, and then select the Propagate Settings command. In the Propagate Folder Settings dialog box, select the Mail Enabled check box, and then click OK.

Mail-Enabled Public Folders and Server-Based Address Lists

Mail-enabled public folders may be hidden from the server-based address lists. If you want to allow your users to select a particular public folder as a message recipient, such as a mail-based discussion forum, you need to make sure that the folder is visible. Launch the Exchange System Manager and display the public folder's properties, switch to the Exchange Advanced tab, and check that the Hide From Exchange Address Lists check box is deselected. This will be the case for all those folders that you have mail-enabled explicitly. However, if you have propagated the mail-enabled configuration from a parent folder to its sub-folders, these sub-folders are hidden by default.

Mail-Enabled Public Folders as Message Archives

It is possible to add a mail-enabled public folder to a distribution group (Member Of property sheet in Exchange System Manager), which allows you to keep track of discussions in teams, workgroups, and so forth. This frees team members from having to maintain personal discussion folders for distribution lists. In addition, you can revoke permissions to delete items from all members and implicitly create an authentic tracking system. Users must have the right to create items in a public folder if they want to send messages to it. Otherwise, a nondelivery report will inform the sender about the missing permissions.

NOTE


You can forward all messages sent or received by users on a particular mailbox store to a mail-enabled public folder. To achieve this, display the mailbox store's General tab, select the Archive All Messages Sent Or Received By Mailboxes On This Store check box, and select the desired folder. Because the Information Store service performs the archiving in the context of the LocalSystem account, users do not require any permission on the archiving folder.

Public Folders As Mailing List Members

List servers automatically distribute e-mail messages that have been sent to a particular address to all members of the list. The message volume can be large, filling your mailbox unnecessarily. If this situation sounds familiar to you, you might want to subscribe a public folder instead of your personal mailbox to the list. As mentioned earlier, the e-mail addresses of a public folder are listed in the E-Mail Addresses tab in the public folder's properties. Just provide the SMTP address of the desired public folder to the list server, and the list server sends all messages to the corresponding folder. You can view and filter them, and share them with colleagues easily (see Figure 17.3). Old items can also be purged automatically based on age limits. Make sure that the desired public folder is visible in the server-based address lists.

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Figure 17.3 Subscribing public folders to list servers

Organizational Units for Mail-Enabled Public Folders

Mail-enabled public folders are associated with recipient objects, which can be displayed in Active Directory Users and Computers. Make sure the Advanced Features option is active, and then, in the console tree, select the container called Microsoft Exchange System Objects. In this location, you can change display names and manage group memberships. You can also move a public folder to another organizational unit, if desired.

NOTE


If you want to move a public folder back into the Microsoft Exchange System Objects container, click View in the toolbar and select the Users, Groups, And Computers As Containers option. Otherwise, the Microsoft Exchange System Objects container is not listed in the Move dialog box.

Directory Names for Public Folders

Active Directory and the Information Store service maintain information about mail-enabled public folders in different ways. The Information Store is responsible for hierarchy and content, whereas Active Directory cares about directory-related issues. Both are synchronized with each other, yet Active Directory does not maintain a hierarchy for public folders as the Information Store does. The missing hierarchical structure does not lead to a conflict when generating directory names, yet users may find it puzzling if public folders with the same display names are listed in their address books.

To give an example, if you create a new top-level public folder in Exchange System Manager, call it DuplicateFolder, and mail-enable it, you can verify that it is only seconds before a corresponding recipient object is listed in Active Directory Users and Computers. Now, create a sub-folder under DuplicateFolder and give it the same name of DuplicateFolder. After that, mail-enable this folder as well, and then check the folder name in Active Directory Users and Computers. You will find that an arbitrary number was appended to the directory name to create a unique second public folder recipient object. The format is DuplicateFolder 12345678. When you check the information in the address book of Outlook 2000, however, you will find two public folders called DuplicateFolder. Because display names do not need to be unique, an arbitrary number is not appended. It is possible to change the display name of a public folder in Active Directory Users and Computers (Folder Display Name setting/General tab).

Replication Latency Issues

Using e-mail messages, the Information Store service replicates public folder hierarchies to all servers with associated public stores. The replication of recipient objects, on the other hand, is the task of Active Directory. Hence, two independent processes replicate information about a single object. Depending on which process is completed first, a mail-enabled public folder may first become visible to all other servers in either the directory or the public folder hierarchy. As time goes by, differences in listed public folders will disappear, but it might create some confusion in the meantime.

NOTE


If you want to compare the hierarchy of a particular public store with other stores, right-click the desired hierarchy object in Exchange System Manager (such as Public Folders), and select Connect To. In the Select A Public Store dialog box, choose the public store that you want to examine.

Mail-Disabling Public Folders

It is possible to delete a public folder recipient object from the Microsoft Exchange System Objects container, in which case you mail-disable the affected folder. However, in Exchange System Manager, the state of the public folder will remain mail-enabled. Therefore, it is not advisable to use Active Directory Users and Computers for this purpose. Exclusively, use Exchange System instead. Right-click the desired mail-enabled public folder, point to All Tasks, and then select the Mail Disable command.

NOTE


If you have deleted a public folder recipient object in Active Directory Users and Computers, do not forget to complete the process of mail-disabling the folder in Exchange System Manager.

Exercise 1: Creating Public Folder Hierarchies

In this exercise you will create an additional public folder hierarchy using Exchange System Manager. You will associate it with a public store.

To view a multimedia demonstration that displays how to perform this procedure, run the EX1CH17*.AVI files from the \Exercise_Information\Chapter17 folder on the Supplemental Course Materials CD.

Prerequisites

  • It is assumed that you have deleted the default public store from BLUESKY-SRV2 as outlined in Exercise 1 of Chapter 14, "Managing Server Configuration." If you did not follow this exercise, skip the steps to recreate the default public store.
  • Display administrative and routing groups in Exchange System Manager (Display Routing Groups and Display Administrative Groups in the properties of the organization object).
  • Make sure BLUESKY-SRV1and BLUESKY-SRV2 are running.
  • Log on as Administrator to BLUESKY-SRV1and BLUESKY-SRV2.

To create public folder hierarchies and associate them with public stores

  1. On BLUESKY-SRV2, launch Exchange System Manager, expand Administrative Groups, then First Administrative Group, then Servers, then BLUESKY-SRV2, and then right-click First Storage Group. Point to New and select Public Store.
  2. In the Properties dialog box, under Name, type Public Folder Store (BLUESKY-SRV2).
  3. Under Associated Public Folder Tree, click Browse, and, in the Select Public Folder Trees dialog box, double-click Public Folders (see Figure 17.4).

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    Figure 17.4 Creating a public store for the MAPI-based hierarchy

  4. Click OK, and, in the Public Folder Store (BLUESKY-SRV2) dialog box asking you whether you want to mount this store now, click Yes.
  5. In the Public Folder Store (BLUESKY-SRV2) dialog box informing you that the store was successfully mounted, click OK.
  6. Open the First Storage Group container, verify that the Public Folder Store (BLUESKY-SRV2) exists, right-click Mailbox Store (BLUESKY-SRV2), and select Properties.
  7. In the General tab, under Default Public Store, click Browse, and select Public Folder Store (BLUESKY-SRV2) - BLUESKY-SRV2. Click OK twice.
  8. If a VIP Mailboxes store exists in the Management Group (created in Exercise 1 of Chapter 14, "Managing Server Configuration"), repeat Steps 6 and 7 to assign this mailbox store the public store on BLUESKY-SRV2 as the default public store.

    At this point, you have recreated the public store on BLUESKY-SRV2 and assigned this store to all existing mailbox stores on this server as the default public store, which corresponds to a default configuration. Close Exchange System Manager.

  9. On BLUESKY-SRV1, launch Exchange System Manager, expand Administrative Groups, then First Administrative Group, then Folders, and verify that Public Folders is listed. Public Folders is currently the default MAPI-based hierarchy, which is associated with public stores on BLUESKY-SRV1 and BLUESKY-SRV2.
  10. Right-click Folders, point to New, and select Public Folder Tree.
  11. In the Properties dialog box, under Name, type Alternate Tree. Notice that General Purpose is displayed under Folder Tree Type, and click OK. A new hierarchy is now listed below Public Folders.
  12. Expand Servers, then BLUESKY-SRV1, then right-click First Storage Group. Point to New and select Public Store.
  13. In the Properties dialog box, under Name, type Alternate Public Store, and, under Associated Public Folder Tree, click Browse.
  14. Notice that only the new folder hierarchy is listed. The Public Folders tree is already associated with the Public Folder Store (BLUESKY-SRV1) and cannot be associated with a second public store at the same time (see Figure 17.5). Select Alternate Tree and click OK. Click OK again to close the Properties dialog box.
  15. An Alternate Public Store dialog box will be displayed, asking you whether you want to mount this store now. Click Yes.
  16. In the Alternate Public Store dialog box informing you that the store was mounted successfully, click OK.
  17. On BLUESKY-SRV1, launch Windows Explorer, expand drive M, expand Bluesky-inc-10.com, select Alternate Tree, open the File menu, point to New, and click Folder.

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    Figure 17.5 Creating an alternate hierarchy and public store

  18. Name the new public folder BLUESKY-SRV1 Only, and press ENTER.
  19. On BLUESKY-SRV2, launch Windows Explorer, expand drive M, expand Bluesky-inc-10.com, and notice that the Alternate Tree is not displayed because this server does not hold a public store associated with the alternate hierarchy (see Figure 17.6).

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    Figure 17.6 Working with different hierarchies on different servers

Exercise Summary

After creating a hierarchy, you need to create a public store to host the tree. Public folder hierarchies can be associated with exactly one public store per server. If multiple servers maintain a public store for the same hierarchy, the hierarchy is automatically replicated. If you create an alternate hierarchy and do not associate it with multiple stores from different servers, no replication takes place. The hierarchy is then available on the local server only.



MCSE Training Kit Exam 70-224(c) Microsoft Exchange 2000 Server Implementation and Administration
MCSE Training Kit Exam 70-224(c) Microsoft Exchange 2000 Server Implementation and Administration
ISBN: N/A
EAN: N/A
Year: 2001
Pages: 186

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