HOW TO: Configure Storage Limits on Mailboxes in Exchange 2000 (319583)

SUMMARY

This step-by-step article describes how to configure storage limits on the mailbox store and individual mailboxes in Exchange 2000. If you use Exchange 2000 with a Microsoft Outlook client computer, you may store an excessive amount of mail. If many users in your organization have a large amount of stored mail, you may create large storage demands on your Exchange 2000 computers. Large mailbox stores lead to long backup and restore times, which affects the availability and reliability of your Exchange 2000 environment. Microsoft recommends that you control the size of users' mailboxes to avoid a situation in which you run out of storage space.

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Requirements

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

• Microsoft Windows 2000 Server with Service Pack 2 (SP2)
• Active Directory
• Exchange Server 2000 with Service Pack 1 (SP1)

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

• Exchange System Manager
• The mailbox sizes that your users need to have to carry out their jobs

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Planning Mailbox Store Limits

If you implement Exchange 2000, you must plan the limit that you want to set for the maximum size of a mailbox. The following list describes the reasons why it is important to plan the mailbox storage limits:

• Although Exchange 2000 Enterprise edition removes the 16-gigabyte (GB) limit on an individual mailbox store, there are practical limits for backing up and restoring databases. Microsoft recommends that you use a 35-GB limit (approximately) for a single mailbox store.
• The multiple database and storage group feature of the Exchange 2000 Enterprise edition allows you to have multiple mailbox stores. However, be aware that you can only back up one database in a storage group at any one time (although you can back up multiple storage groups at the same time). At maximum capacity, you may have to back up 35 GB five times in your available backup window.
• 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 at least 10 percent. For example, a 35-GB database runs on an 80-GB partition.
• You configure mailbox limits on the mailbox store; however, you can configure an individual user's mailbox to override the limits that you set on the mailbox store.
• Users always use the mailbox space that is allocated to them. For example, if configure the mailboxes to have a limit 500 megabytes (MB), users eventually use all of this space.

In addition, consider the following factors if you configure mailbox limits:

• Plan on a hierarchy of mailbox sizes, for example, configure a 100-MB limit for ordinary users, a 200-MB limit for power users, and a 300-MB limit for administrators. You can implement these limits on three different mailbox stores.
• If you have users who have storage requirements outside these limits, you can configure limits for individual mailboxes.
• Remember that the deleted item retention time also affects the size of a mailbox store because items are not actually deleted until after the deleted item retention time has expired.

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How to Set Limits on a Mailbox Store

To set limits on a mailbox store:

1. Click Start, point to Programs, point to Microsoft Exchange, and then click System Manager.
2. In the left pane, expand the Exchange 2000 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 mailbox store that you want to configure, and then double-click Storage group in the right pane.
4. Right-click the mailbox store that you want to configure, click Properties, and then click the Limits tab.
5. Click to select one or all of the following check boxes under Storage limits:
   
   
   • Issue warning at: Select this check box to warn the user that their mailbox has exceeded its limit. However, normal functioning of the mailbox continues.
   • Prohibit send at: Select this check box to send a warning message that states that the user will not be able to send any more messages until they delete or archive their old mail. However, users can still receive messages.
     
     NOTE: Type a value (in kilobytes [KB]) for the size of the mailbox, for example, 100,000 KB for normal users or 200,000 KB for the power users.
   • Prohibit send and receive at: Select this check box to send a warning message that states that the user has exceeded mailbox limits. If the user receives this message, the user cannot receive any messages.
     
     NOTE: Type a value (in kilobytes [KB]) for the size of the mailbox, for example, 100,000 KB for normal users or 200,000 KB for the power users.
   If you have a limit of 100,000 KB on the mailbox, set the Prohibit send at setting to 110,000 KB and the Prohibit send and receive at setting to 120,000 KB. However, if 100, 000 KB really is the limit that you can give everyone, set the Issue warning at setting to 90,000 KB, the Prohibit send at setting to 95,000 KB, and the Prohibit send and receive at setting to 100,000 KB.
6. Either 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 then click a time on the top row or click and hold the mouse button as you sweep across the time slots to configure warning settings.
   
   NOTE: To configure the schedule to be displayed in hour slots or in 15-minute slots, click the appropriate option under Detail View.
8. After you configure the warning message interval times, click OK.
9. If you want maximum control of your database sizes, configure the Keep deleted items for (days) setting to 0. Otherwise, Microsoft recommends that you a configure this setting to 7 days.

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How to Set Limits on Individual Mailboxes

All mailboxes that have a mailbox store have the same limit that is set on that mailbox store. However, you can configure individual mailbox limits to override the limits that you set for the mailbox store.

1. Click Start, point to Programs, point to Microsoft Exchange, and then click Active Directory Users and Computers.
2. In the left pane, expand Domain, and then expand Organizational units.
3. Open the organizational unit that contains the mailbox that you want to configure.
4. Right-click the mailbox, and then click Properties.
5. Click the Exchange General tab, and then click Storage Limits.
   
   The Use mailbox store defaults check box is selected and the mailbox limits are shaded by default.
6. Click to clear the Use mailbox store defaults check box, and then configure either the Issue warning at setting, the Prohibit send at setting, or the Prohibit send and receive at setting as required on this mailbox.
7. Optionally, click to clear the Use mailbox store defaults under Deleted Item Retention to configure different settings for this mailbox.
8. Click OK, and then click OK.

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How to Confirm That You Set Mailbox Storage Limits Correctly

To confirm that the mailbox store limits work, change the generate warnings schedule to run constantly, create a dummy user account and mailbox, and then add messages to that mailbox until the warning messages are displayed. You may receive the warning message up to 15 minutes after you have added the messages. After you exceed the Prohibit send and receive setting, any messages that you send to the test account are returned as undeliverable.

After you confirm the mailbox store limits, configure different mailbox limits for the test user, log off Outlook, and then log on again. The mailbox receives mail again.

NOTE: To check for folder sizes in Outlook:

1. Log on to the Outlook client computer.
2. In the Folder List column, right-click Outlook Today, and then click Properties for Mailbox (User Name).
3. Click the General tab, and then click the Folder Size.

To check folder sizes in Exchange System Manager, click the Mailboxes object under Mailbox Store (Servername) in the left pane. The mailboxes 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 finish testing, reset the schedule to generate warning messages.

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Troubleshooting

If you configure storage limits, note that the mailbox limits are measured in KB and not megabytes (MB). If you do not make this distinction, you may type 100 KB instead of 100,000 KB as the mailbox limit.

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