Topic Last Modified: 2005-11-17

The Microsoft® Exchange Server Analyzer Tool queries the Active Directory® directory service to determine the value for the garbageCollPeriod attribute of each mailbox store. If the Exchange Server Analyzer finds that the garbageCollPeriod attribute is set to 0 for any mailbox store, a best practice recommendation message is displayed.

Garbage collection is an internal Exchange housekeeping process that frees space within the mailbox store database. By default, deleted items are stored in the mailbox store database for a certain number of days before they are permanently deleted by Exchange. You can set the length of the deleted item retention period by either using the mailbox store defaults, or by selecting the number of days that a deleted item is kept before it is permanently deleted.

You can select a number from 0 to 24,855 when specifying the number of days to retain a deleted item. It is recommended that you configure this setting to 7 days. If the deleted item retention period is set to 0, the deleted items are permanently removed from the server immediately. Unless disk space is an issue, it is recommended that you do not disable the deleted item retention feature. Follow the procedures below to specify the number of days that deleted items are stored before they are permanently deleted.

To configure deleted item retention in Exchange System Manager
  1. Open Exchange System Manager.

  2. Expand Administrative Group or Organization, click Servers, and then click Mailbox Store.

  3. Right-click the mailbox store, and then click Properties.

  4. On the Limits tab, set the deleted items retention period by doing the following:

    • To set a retention period for deleted items, click Keep deleted items for (days), and then type a value.

    • To preserve items until backup, click Do not permanently delete mailboxes and items until the store has been backed up.

To configure deleted item retention in Active Directory Users and Computers
  1. Open Active Directory Users and Computers.

  2. In the console tree, expand the domain.

  3. Double-click Users, or double-click the node that contains the recipient information that you want to modify.

  4. In the details pane, double-click the recipient that you are modifying.

  5. On the Exchange General tab, click Storage Limits.

  6. In the Storage Limits dialog box, under Deleted item retention, click to clear the Use mailbox store defaults check box, and then in Keep deleted items for (days), type a value.

    To prevent deleted items from being permanently deleted before they are backed up, select the Do not permanently delete items until the store has been backed up check box.

For more information about setting mailbox storage limits, see the Microsoft Knowledge Base article 319583, "HOW TO: Configure Storage Limits on Mailboxes in Exchange 2000" (