KB17325 - View Document
As of Windows Server 2008, Microsoft has changed the default behavior of the Domain Controller with regards to Named Service Provider Interface (NSPI) connections. NSPI is the interface that allows Messaging Application Programming Interface (MAPI) to interact with the Global Catalog server to use the Microsoft® Exchange address book and to perform name resolution tasks requiring the information stored in the Global Catalog. Prior to Windows Server 2008, any individual MAPI client could make virtually unlimited number of NSPI connections to a Global Catalog without consequence. In order to more appropriately manage these connections from MAPI clients, Windows Server 2008 introduced a limit of 50 NSPI connections per user. For more details, see Microsoft Knowledge Base article 949469 at the Microsoft Support web site.
This limit has little to no impact on a single user MAPI client; however, the BlackBerry Enterprise Server has to monitor the mailbox for each user that is added to it and therefore requires more NSPI connections than a client, such as Microsoft® Outlook® would.
In order to limit the impact of this issue, if there are multiple BlackBerry Enterprise Servers in the environment they can be run under different service accounts. However, if this has already been done it may be necessary to increase the limit on the number of NSPI connections per user. First, get final confirmation that the limit on NSPI connections is the cause of the issue (See the Additional Information section to determine this). Once that has been confirmed, the issue can be worked around by taking the following steps:
1. Click Start, click Run, type regedit, and then click OK.
2. Locate the following registry key: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Servic es\NTDS
3. On the Edit menu, point to New, and then click Key.
4. Type Parameters, and then press ENTER.
5. Click the Parameters key.
6. On the Edit menu, point to New, and then click DWORD Value.
7. Type NSPI max sessions per user, and then press ENTER.
8. Dlb-Clk NSPI max sessions per user, type the max number of NSPI connections that you want to have, and then click OK.
9. Exit the Registry Editor.
This should be done on any Global Catalog Server that the BlackBerry Enterprise Server may be required to connect to (for example, all Global Catalog Servers in the same site as the service account mailbox).
Also see: NSPI connections to a Windows 2008-based domain controller may cause MAPI client applications to fail with an error codexxx58; xxx34;MAPI_E_LOGON_FAILEDxxx34; Errorxxx58; xxx34;Trying to connect to Microsoft Exchange Serverxxx34; results in MAPI_E_LOGON_FAILED