Well we all have users with ENORMOUS mailboxes - even though there are no practical limits on mailbox size we all know that there are many more variables that influence the "actual" performance of email access (lan speeds, PC age, Exchange server sizing, etc)
We came across this at a few sites and the following helped us get around it.
Description:
This is caused by a very high usage level by an individual user. If these errors are happening regularly, you can raise the default maximum for the affected object type (for example, to twice its default level). If at this level the specified user is continuing to generate this warning, investigate the user actions that are causing this warning. It can be caused by improper client design or unusual client usage patterns.
Resolution for Exchange 2007
To resolve the problem, do the following:
•Investigate any third-party applications or add-ins that are running on the MAPI client. Some third-party applications keep objects open for long periods of time or open many objects concurrently.
(Blackberry server, Virus Scanners for Email Servers -- always run a separate gateway not on SERVER!!!)
•Investigate the user behavior that is associated with the indicated logon. This will help you better understand why the default number of objects is insufficient.
•In rare cases, you may need to add a registry key to adjust the maximum number of open objects. This new registry key will override the default value. Such rare cases include situations in which it is acceptable or necessary to use applications that keep objects open or open many objects concurrently.
Caution:
When you increase the maximum number of an object type, you also increase the memory that may be consumed by all client requests connecting to the server. Incorrectly configuring this value could lead to out-of-memory warnings or virtual memory fragmentation warnings.
Caution:
Incorrectly editing the registry can cause serious problems that may require you to reinstall your operating system. Problems resulting from editing the registry incorrectly may not be able to be resolved. Before editing the registry, back up any valuable data.
Before You Begin
To perform the following procedure, the account you use must be delegated membership in the local Administrators group. For more information about permissions, delegating roles, and the rights that are required to administer Exchange 2007, see Permission Considerations.
Procedure
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.
Note:
The server will automatically recognize the new limit within five minutes.
