On a server that is running Microsoft Exchange Server 2003,
an event that resembles the following event is logged in the Application
Event Source: MSExchangeIS
Event Category: General
Closing Mapi session
because it exceeded the maximum of 32 objects of type "session".
this issue occurs, you may also receive the following error message in
Microsoft Office Outlook 2003:
Unable to open your default
e-mail folders. The Microsoft Exchange Server computer is not available. Either
there are network problems or the Microsoft Exchange Server is down for
This issue may occur if the following conditions are true:
- You have installed Microsoft Exchange Server 2003 Service
Pack 1 (SP1) on the Exchange Server computer.
- A program that is running on a client computer opens many
MAPI sessions to the Exchange Server computer. The number of MAPI sessions is
larger than the permitted limit.
- You are using Microsoft Office Outlook 2007, and you add a
large additional mailbox to your profile. For example, this issue may occur if
the additional mailbox contains more than one thousand folders.
Exchange Server 2003 SP1 imposes a restriction on the number of
permitted MAPI sessions per user. By default, the maximum number of permitted
MAPI sessions per user is set to a hexadecimal value of 0x20 after you apply
Exchange Server 2003 SP1.Note
A hexadecimal value of 0x20 converts to a decimal value of
To resolve this issue, we recommend that you first determine
whether the MAPI session limit is reached because of potential abuse, because a
large additional mailbox was added, because it is the result of a bug in a
client program, or because of client program design.
If the issue
occurs because a large mailbox was added to a Cached Exchange Mode profile in
Outlook 2007, you can disable the new Outlook 2007 default feature that causes
this issue. To do this, follow these steps. Note
When you follow these steps, you cannot access the shared mailbox
folders while you are working offline by using your Cached Exchange Mode
- On the Tools menu, click Account
- Click the Exchange Server account, and then click
- Click More Settings.
- On the Advanced tab, click to clear the
Download shared folders (excludes mail folders) check box.
- Click OK, click Next,
and then click Finish.
If the issue occurs because of a bug in a client program or
because of client program design, we recommend that you contact the vendor to
determine whether you can use one of the following procedures:
- Obtain a fix
- Grant View Information Store Status permissions to the
account under which the program runs
Note Programs that run under an account that has these permissions are
not affected by the MAPI sessions-per-user limit.
To grant View Information Store Status permissions, follow
- In Exchange System Manager, right-click the Exchange Server
object or the mailbox store to which you want to grant the permissions, and
then click Properties.
- Click the Security tab.
- Click the account to which you want to grant the
If the account is not listed, click
Add, click the account name, click Add, and
then click OK.
- Under the Allow column, click to select
the View information store status check box, if this check box
is not already selected.
- Click to clear the check boxes for any permissions that are
not required, and then click OK.
Note You may have to follow this step if you clicked
Add to add the account in step 3. This is because every check
box in the Allow column was selected when you added the
account in step 3.
If you cannot obtain a fix, and if you cannot configure the
account to run together with View Information Store Status permissions, you can
adjust the number of MAPI sessions per user that are permitted by configuring
the registry settings. If you do this, try to determine the minimum value that
you can use so that the client program can run without problems. If you raise
the limit too high, the client program might affect the performance of the
Exchange Server computer.
If this issue occurs after you install the
Scalable Networking pack or Windows 2003 Service Pack 2, see the following
article in the Microsoft Knowledge Base:
You may experience network-related problems after you install Windows Server 2003 SP2 or the Scalable Networking Pack on a Windows Server 2003-based computer
To change the value of the maximum permitted MAPI sessions
per user from the default, you can configure the Maximum Allowed Sessions Per
User registry entry. To do this, follow these steps.Important
This section, method, or task contains steps that tell you how to
modify the registry. However, serious problems might occur if you modify the
registry incorrectly. Therefore, make sure that you follow these steps
carefully. For added protection, back up the registry before you modify it.
Then, you can restore the registry if a problem occurs. For more information
about how to back up and restore the registry, click the following article
number to view the article in the Microsoft Knowledge Base:
How to back up and restore the registry in Windows
- Click Start, click Run,
type regedit in the Open box, and then
- Locate and then click the following registry subkey:
- If the Maximum Allowed Sessions Per User
entry does not exist, do the following:
- On the Edit menu, point to
New, and then click DWORD Value.
- Type Maximum Allowed Sessions Per
User as the entry name, and then press ENTER.
- Right-click the Maximum Allowed Sessions Per
User entry, and then click Modify.
- Click Decimal, type the value that you
want to set in the Value data box, and then click
- Exit Registry Editor.
- Click Start, click Run,
type services.msc in the Open box, and
then click OK.
- Click the MSExchange Information Store
service, and then click Restart Service.
Article ID: 842022 - Last Review: June 16, 2008 - Revision: 5.1
- Microsoft Exchange Server 2003 Standard Edition
- Microsoft Exchange Server 2003 Enterprise Edition
- Microsoft Exchange Server 2007 Enterprise Edition
- Microsoft Exchange Server 2007 Standard Edition