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Outlook 2000, 2003, 2007 problems

When running Exchange 2003 or Exchange 2007. A Exchange 2007 users can no longer logon their mailbox using MAPI. They can using OWA and if I give another user full mailbox access this user has no problem logging on using MAPI.

Creating a new Outlook 2003 profile gives same error and a new NT profile does also give same error.

Mapi session “/o=First Organization/ou=First Administrative Group/cn=Recipients/cn=” exceeded the maximum of objects of type ““.

Event ID: 9646
Source     MSExchangeIS
Type     Error
Description     Mapi session “/o=First Organization/ou=First Administrative Group/cn=Recipients/cn=<account name>” exceeded the maximum of <number> objects of type “<type>”.

Windows 2003 SP2 introduced a feature called scalable networking. Disabling it immediately fixed the problem of Outlook clients using too many sessions. To disable without rebooting enter the following at a command prompt on your Exchange Server:
Fixes: netsh int ip set chimney disabled - the problem disappeared instantaneous.

To permanently disable (reboot required), set the following registry value to 0:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\EnableTCPChimney.

The Microsoft Windows Server 2003 Scalable Networking Pack release

http://support.microsoft.com/kb/912222

http://technet.microsoft.com/en-us/library/bb878074.aspx

Event ID 9646 is logged in the application event log of your Exchange Server 2003 computer when a client opens many MAPI sessions

http://support.microsoft.com/default.aspx?scid=kb%3Ben-us%3B842022

How to know if TCP offload is working

C:\>netsh int tcp show global

Windows 2003 its a bit different:

Netsh int ip set chimney DISABLED

Netsh int ip set chimney ENABLED

http://en.wikipedia.org/wiki/TCP_Offload_Engine

To use Registry Editor to adjust the maximum number of open objects that a MAPI client can use at the same time

1. Start Registry Editor (regedit).

2. Locate the following registry subkey: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem

3. Right-click ParametersSystem, point to New, and then click Key.

4. Type MaxObjsPerMapiSession, and then press ENTER to name the new subkey.

5. Right-click MaxObjsPerMapiSession, click New, and then click DWORD Value.

6. Type the object type, and then press ENTER to name the entry. For example, type objtMessage, and then press ENTER to create an entry that changes the default maximum of objtMessage objects.

7. Right-click the entry that you created in Step 6, and then click Modify.

8. In the Value data box, type the new maximum number of objects to which you want to limit this entry, and then click OK.

http://technet.microsoft.com/en-us/library/bb676486(EXCHG.80).aspx