Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool reads the following registry entry to determine whether Mailbox Cache Size is present:


If the Exchange Server Analyzer finds the Mailbox Cache Size registry entry present, a non-default configuration message is displayed.

The Mailbox Cache Size value controls the size of this mailbox cache. The default value is 256 MB. Exchange Server allows size limits (quotas) to be set on mailboxes. Quota settings are stored in the Active Directory® directory service and Exchange Server periodically reads the information in Active Directory to determine whether any changes were made to these limits. By default, Exchange Server caches this information for a period of two hours (7,200 seconds), after which it re-reads the information in Active Directory.

This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore the registry if a problem occurs. For information about how to restore the registry, view the "Restore the Registry" Help topic in Regedit.exe or Regedt32.exe.

To revert to the default configuration

  1. Open a registry editor, such as Regedit.exe or Regedt32.exe.

  2. Navigate to:


  3. In the right pane, locate and delete the Mailbox Cache Size value.

  4. Close the registry editor and restart the Microsoft Exchange Information Store service for the change to take effect.

Before you edit the registry, and for information about how to edit the registry, see the Microsoft Knowledge Base article 256986, "Description of the Microsoft Windows Registry" (

For more information about the Mailbox Cache Age Limit registry value, see the Knowledge Base article 327378, "XADM: Exchange 2000 Mailbox Size Limits Are Not Enforced in a Reasonable Period of Time; Fix Requires Exchange 2000 SP3" (