Important If you increase the MaxObjsPerMapiSession value, it can have a significant performance affect on the Microsoft Exchange server. Specifically, if the batch file or the script that you used to send the messages or the attachments does not correctly close out MAPI sessions, no clients can log on to the Exchange server if you have increased the MaxObjsPerMapiSession value. We recommend that you correct the batch file or the script instead of changing the MaxObjsPerMapiSession value.
Note Microsoft Exchange Server 2003 Service Pack 1 (SP1) increases the default values of the object types that are listed in the "More Information" section. This behavior is referenced in the following Microsoft Knowledge Base article:
- On the Exchange 2003 computer, click Start, click Run, type regedit in the Open box, and then click OK.
- Locate and then click the following registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem
- On the Edit menu, point to New, and then click Key.
- Type MaxObjsPerMapiSession, and then press ENTER.
- For each object type that is listed in the event ID 9646 message (in the "Symptoms" section of this article, the example object types are objtMessage and objtAttachment), follow these steps:
- On the Edit menu, point to New, and then click DWORD Value.
- Type the object name (for example, type objtMessage), and then press ENTER.
- Press ENTER again to open the Edit DWORD Value dialog box, type 500 in the Value data box, and then click OK.
- Close Registry Editor.
- A program
- An Outlook add-in
- A script or batch file
- Click Start, point to All Programs, point to Microsoft Exchange, and then click System Manager.
- If Administrative Groups is listed, expand Administrative Groups, and then expand First Administrative Group. If Administrative Groups does not appear, go to step 3.
- Expand Servers, expand your Exchange computer, expand First Administrative Group, and then expand Mailbox Store.
- Click Logons, click the View menu, and then click Add/Remove Columns.
- In the Available columns dialog box, click Open Messages, and then click Add.
- In the Available columns dialog box, click Open Attachments, click Add, and then click OK.
- Click Logons, click the Action menu, click Export list, type the name of the Mailbox Store in the Save As dialog box, and then click Text (Comma Delimited)(*.csv) and Save in the Save as type drop-down box.
- Repeat this process for each Mailbox Store.
After the data is collected, follow these steps:
- Open the files in Microsoft Excel.
- Sort each column.
As mentioned previously, this problem may be caused by a program that integrates with Outlook, with an Outlook add-in, or with a batch file or script that is running against the mailbox.
As a further troubleshooting step, remove or disable any third-party Outlook add-in and antivirus software on the client computer. Then, verify the results of the server again to ensure that these objects are no longer open.
Article ID: 830836 - Last Review: Mar 29, 2017 - Revision: 3