How to configure storage limits on Public Folders in Exchange 2003

This step-by-step article describes how to configure storage limits on both public folder stores and individual public folders in Exchange 2003. Typically, the storage limit on public folders is not a significant issue because messages that are posted to public folders are typically text-based messages. However, if your organization uses public folders regularly, particularly to store items with attachments or to subscribe to Internet newsgroups, you may want to configure storage limits on public folders in addition to configuring storage limits on mailboxes.

Requirements

The following list outlines the recommended hardware, software, network infrastructure, and service packs that you require:

• Microsoft Windows 2000 Server with Service Pack 3 (SP3) or Microsoft Windows Server 2003
• The Microsoft Active Directory directory service
• Exchange Server 2003

This article assumes that you are familiar with the following topics:

• Exchange System Manager
• The mailbox sizes that your users require

How to Plan Public Folder Limits

If you plan to use the public folders regularly, Microsoft recommends that you consider the maximum size of these folders and then implement the limits before you make the folders available to users. This order is important for a number of reasons:

• MAPI clients such as Microsoft Outlook can only use the default public folder tree. This public folder tree is associated with the default public folder store in the first storage group that is created on each Exchange 2003 computer. If you want all your public folders to be accessible over MAPI, you have to limit yourself to one public folder store for each server.
• Although Exchange 2003 Enterprise Edition removes the 16-gigabyte (GB) limit on an individual mailbox store, there are practical limits when you back up and restore databases. Microsoft recommends that you use a 50-GB limit (approximately) for a single mailbox store.
• Public folders are frequently used as archives. Therefore, they frequently fill up eventually unless controls are implemented.
• You can configure expiration policies on public folders to delete messages that are older than a certain age. However, this procedure is not appropriate for certain types of public folders, such as folders that store contact details.
• You may want to configure the limits on a typical public folder that is used for simple messages to 20 megabytes (MB) and the limits on an archive folder to 100 MB. However, you may not want to configure the limits on a contacts folder (to make the space unlimited).
• Like mailbox limits, you configure public folder limits on the public folder store. However, you can configure individual public folder limits to override the limits that you set on the store.
• To perform an in-place restore, Microsoft recommends that your disks have at least as much free space as the size of the database itself plus 10 percent. For example, a 35-GB database runs on an 80-GB partition.
• Remember that the deleted item retention time also affects the size of a public folder store, because items are not actually deleted until after the deleted item retention time has expired.

How to Set Limits on Public Folder Stores

You use a slightly different procedure to set limits on public folder stores than the procedure that you use to set limits on a mailbox store, because you cannot set the Prohibit Send setting on a public folder.

1. Click Start, point to Programs, point to Microsoft Exchange, and then click System Manager.
2. In the left pane, expand the Exchange 2003 hierarchy until you find the Servers container.
   
   If an Administrative Groups container is displayed, the Servers container is under the respective administrative group.
3. Expand the Servers container, click the server that hosts the public folder store that you want to configure, and then in the right pane, double-click Storage group.
4. Right-click the public folder store that you want to configure, click Properties, and then click the Limits tab.
5. Under Storage limits, click to select one or all of the following check boxes:
   1. Issue warning at: Click to select this check box to warn the users who have public folder Owner or Folder Contact roles that their public folder has exceeded its limit. However, the public folder continues to function.
   2. Prohibit post at: Click to select this check box to prevent new messages from being posted to the folder if the folder reaches the size that you specify.
   3. Maximum item size: Click to select this check box to prevent anyone from posting messages that are larger than a certain size, regardless of how full the folder is.
      
      Note Type the size value in kilobytes (KB) for the majority of the public folders that are hosted in this store. For example, type 20,000 KB for the limit of a message-based public folder, and type 100 KB for the Maximum item size setting.
6. To configure warning settings, click the time that you want the warning messages to be generated in the Warning message interval box, or click Customize.
7. If you click Customize, either click a day in the left column and a time on the top row, or click and hold the mouse button as you sweep across the time slots.
   
   Note To configure the schedule to be displayed in 1-hour slots or in 15-minute slots, click the appropriate setting under Detail View.
8. If you click Customize, click OK after you configure the warning message interval times.
9. If you want maximum control of your database sizes, configure the Keep deleted items for (days) setting to 0 (zero). Otherwise, Microsoft recommends that you configure this setting to seven days. Deleted item retention time is more important on public folders, where items are deleted immediately and are not sent to the Deleted Items folder.
10. After you finish configuring public folder store limits, click OK.

How to Set Limits on Individual Public Folders

You can configure individual public folder limits on a folder that exists in the public folder store to override the store limits:

1. Click Start, point to Programs, point to Microsoft Exchange, and then click System Manager.
2. In the left pane, expand the Exchange 2003 hierarchy until you find the Servers container.
   
   If an Administrative Groups container is displayed, the Servers container is under the respective administrative group.
3. Expand the Servers container, click the server that hosts the public folder store that you want to configure, and then double-click Storage group in the right pane.
4. Expand the public folder store that you want to configure, and then click Public Folders.
   
   A list of the public folders that are hosted on the selected public folder store is displayed in the right pane.
5. Double-click the public folder that you want to configure, and then click the Limits tab.
   
   By default, the Use public store defaults check box is selected, and the public store limits are shaded.
6. Click to clear the Use public store defaults check box, and then configure the following settings to the limit (in KB) that is required on this public folder:
   • Issue warning at
   • Prohibit post
   • Maximum Item
7. If you want to do so, you can click to clear the Use public store defaults check box under Deletion Settings to configure different settings for deleted items on this public store.
8. Click OK.

In Exchange 2003 SP2, when you create a child Public Folder inside a parent Public Folder, the storage limits of the child folder are not automatically inherited from the parent folder. The only way to manage the storage limit of the child folders is to right-click the parent folder, select All tasks, select Manage settings, select Override settings, and then select Storage limits. Then, the size limits from the parent are also propagated on all the child folders inside the parent folder.

How to Confirm That You Have Set Public Folder Storage Limits Correctly

To confirm that you have configured the public folder limits correctly:

1. Change the generate warnings schedule to run constantly on the public folder store.
2. Change the permissions on a test public folder so that only you can add items to that public folder.
3. Log on to Outlook as yourself, and then add messages and attachments to the public folders until you receive the warning messages.
   
   Note It may be up to 15 minutes after you add the messages or attachments before you receive the warning message.
4. Add messages that have attachments that are greater than the size limit.
   
   These messages cannot be saved to the folder.

If you go above the prohibit post limit, any messages that you send to the public folders are returned as undeliverable. After you confirm the public folder store limits, use the same procedure to confirm the limits on a public folder where you set individual limits.

To verify the folder sizes in Outlook:

1. Log on to the Outlook client computer.
2. In the Folder List column, expand Public Folders, right-click All Public Folders, and then click Properties.
3. Click the General tab, and then click Folder Size.

To verify the folder sizes in Exchange System Manager, click Public Folders under Public Folder Store (Servername) in the left pane. The Public Folders that are hosted on that store, their size, and the number of items that they contain are displayed in the right pane.

Note After you verify that the limits are correct, reset the generate warnings schedule.

How to Manage the Storage Limit of Child Folders When You Create a Child Public Folder Inside a Parent Public Folder

In Exchange 2003 SP2, when you create a child Public folder inside a parent Public folder, the storage limits of the child folder will not be automatically inherited from the parent folder. The only way to manage the storage limit of the child folders is to right-click the parent folder, click All tasks, click Manage Settings, click Override settings, and then click Storage limits. Then, the size limits from the parent are also propagated on all the child folders inside the parent folder.

Troubleshooting

If you configure storage limits, remember that the public folder limits are measured in KB and not in MB. If you do not make this distinction, you may set the public folder limit to 100 KB instead of 100,000 KB. Additionally, remember that the warning messages are typically generated only one time a day instead of immediately.

For more information about how to configure storage limits in Exchange 2003, see the Exchange Server 2003 Resource Kit and Exchange Server 2003 Help.

The following guided troubleshooting wizard helps you troubleshoot public folder replication problems for Exchange Server 2003.