Knowledge Base

A user who is connected to an Exchange 2003 front-end server by using an IMAP4 e-mail client program may be unexpectedly disconnected from the session

Article ID: 889160

Article Last Modified on 10/25/2007

APPLIES TO

Microsoft Exchange Server 2003 Standard Edition
Microsoft Exchange Server 2003 Enterprise Edition

Important This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SYMPTOMS

When you have Microsoft Exchange Server 2003 configured in a front-end/back-end server environment, you may experience the following problem. A user who is connected to the Exchange 2003 front-end server by using an Internet Message Access Protocol, Version 4rev1 (IMAP4) e-mail client program may be unexpectedly disconnected from the session. When this problem occurs, the user may receive an error message that is similar to the following:

Connection to the host lost.

Press any key to continue.

If this user connects directly to the Exchange 2003 back-end server by using the IMAP4 e-mail client program, the user is not disconnected from the session.

CAUSE

This problem may occur if the following conditions are true:

One or more of the e-mail messages that the user tries to retrieve contain a large header.

Note An e-mail message may have a large header if it has been forwarded many times.

The IMAP4 client program performs a FETCH BODYSTRUCTURE operation or a FETCH BODY operation to parse the e-mail message that contains a large header.

This problem occurs because Exchange 2003 limits the number of embedded MIME message levels that can be processed in an e-mail message. Currently, this limit is 32 levels.

RESOLUTION

Service pack information

To resolve this problem, obtain the latest service pack for Exchange Server 2003. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

836993 How to obtain the latest service packs for Exchange Server 2003

Hotfix information

A supported hotfix is now available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next service pack that contains this hotfix.

To resolve this problem, submit a request to Microsoft Online Customer Services to obtain the hotfix. To submit an online request to obtain the hotfix, visit the following Microsoft Web site:

http://go.microsoft.com/?linkid=6294451

Note If additional issues occur or any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. To create a separate service request, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Prerequisites

You must be running Microsoft Exchange Server 2003 Service Pack 1 (SP1) to install this hotfix. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

836993 How to obtain the latest service packs for Exchange Server 2003

Restart requirement

You do not have to restart your computer after you apply this hotfix. However, many Exchange-related services are automatically stopped and then restarted when you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

Date         Time   Version            Size    File name
--------------------------------------------------------------    
11-Jan-2005  03:40  6.5.7232.67        82,944  Eximap4.dll      
11-Jan-2005  03:40  6.5.7232.67        22,016  Expop3.dll       
11-Jan-2005  03:41  6.5.7232.67        26,112  Exproto.dll      
11-Jan-2005  03:01  6.5.7232.67        27,648  Febecfg.dll      
11-Jan-2005  03:40  6.5.7232.67        23,040  Iisif.dll        
11-Jan-2005  03:42  6.5.7232.67       133,632  Iisproto.dll     
11-Jan-2005  03:42  6.5.7232.67        56,832  Imap4be.dll      
11-Jan-2005  03:02  6.5.7232.67       122,880  Imap4fe.dll      
11-Jan-2005  03:40  6.5.7232.67       119,296  Imap4svc.dll     
11-Jan-2005  03:40  6.5.7232.67        27,136  Pop3be.dll       
11-Jan-2005  03:03  6.5.7232.67        12,288  Pop3fe.dll       
11-Jan-2005  03:36  6.5.7232.67        69,120  Pop3svc.dll

Hotfix installation information

Warning If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

After you install this hotfix, you can use the following new registry value to modify the number of MIME message levels that can be processed in an e-mail message in Exchange 2003:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem\InternetContent

Value name: LimitNestingLevels
Value type: REG_SZ
Value data: 32 through 256

By default, Exchange 2003 permits 32 MIME message levels to be processed in an e-mail message. You can use this registry value to increase this limit to 256 levels.

Installation notes

This hotfix is intended for installation on your Exchange 2003 front-end servers. You do not have to install this hotfix on your Exchange 2003 back-end servers.
The LimitNestingLevels registry value also affects messages that are encoded by using Transport Neutral Encapsulation Format (TNEF), and it affects I-Mail conversion on your Exchange server.

STATUS

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section. This problem was first corrected in Exchange Server 2003 Service Pack 2.

MORE INFORMATION

For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates