Increasing MAPI Property Limits

Some Exchange servers that have been in commissi​on for years may hit MAPI named property limits. These limits are reached when we attempt to retrieve more properties than the server is configured for. You will know if your server reaches these limits as an event similar to the following is logged:

Event Type: Error

Event Source: MSExchangeIS

Event Category: General

Event ID: 9667

Date: 6/11/2010

Time: 4:56:13 PM

User: N/A



Failed to create a new named property for database "First Storage Group\Mailbox Store (SERVERNAME)" because the number of named properties reached the quota limit (8192).

User attempting to create the named property: "SYSTEM"

Named property GUID: 00062002-0000-0000-c000-000000000046

Named property name/id: "33377"


To increase the number of MAPI named properties:

  1. Start the Registry Editor on the mailbox server.
  2. Locate the following registry key:
    • HKLM\SYSTEM\CurrentControlSet\Services\MSExchangeIS\<ServerName>\<Private-GUID>
  3. Set the following DWORD values or create new values if they do not exist.
    • NonMAPI Named Props Quota == 00007fff
    • Named Props Quota == 00007fff

You may either wait approximately 30 minutes for these values to take effect automatically, or reboot the server to take effect immediately.

These instructions have also been documented on the Microsoft website.

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