XFOR: Ability to Restrict Size of Headers Contained in Message

ID: Q193035

The information in this article applies to:

Microsoft Exchange Server, version 5.5

IMPORTANT: This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information about how to do this, view the "Restoring the Registry" Help topic in Regedit.exe or the "Restoring a Registry Key" Help topic in Regedt32.exe.

SYMPTOMS

Messages sent from a Microsoft Exchange Server computer (originating from an Exchange client or through an external gateway) with a large number of recipients may prevent the Microsoft Mail for PC Networks client from downloading new messages. This problem occurs if the messages are directed to one or more recipients on a Microsoft Mail for PC Networks postoffice.

CAUSE

The Microsoft Mail for PC Networks client has a limitation in the size of header that can exist within a message. If a header is larger than 32 KB (or 64 KB with a later fix), the above symptoms will occur. More information about this limitation can be found in the following Knowledge Base article:

Q147040 PC Win: Large Recipient List Stops Download of New Mail

RESOLUTION

To resolve this problem, obtain the latest service pack for Exchange Server version 5.5. For more information, please see the following article in the Microsoft Knowledge Base:

Q191014 XGEN: How to Obtain the Latest Exchange Server 5.5 Service Pack

The English version of this fix should have the following file attributes or later:

Component: Microsoft Mail Connector Interchange


   File Name   Version
   ----------------------
   Mt.exe      5.5.2365.0
   Mtmsg.dll   5.5.2365.0

STATUS

Microsoft has confirmed this to be a problem in Microsoft Exchange Server version 5.5. This problem was first corrected in Exchange Server 5.5 Service Pack 2.

MORE INFORMATION

To work around this limitation, obtain the latest release of the Microsoft Mail Connector Interchange software as indicated above. There is a new registry key called "Message Header Size Limit".

WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it. If you are running Windows NT, you should also update your Emergency Repair Disk (ERD).

Log on to the Microsoft Exchange Server computer where the Microsoft Mail Connector is installed.

Start Registry Editor (Regedt32.exe) and go to the following key:


HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeMSMI
\Parameters

On the Edit menu, click Add Value.

Enter the following:


Value Name: Message Header Size Limit
Data Type:  REG_DWORD
Value:      <see below>

Click OK and quit Registry Editor.

If this registry value is present and set to a positive number, that is the size limit in bytes of the header portion of the MAI file for all outgoing messages from the Microsoft Mail Connector (MSMI). Incoming messages are not affected by this setting. If this registry value is not present or the size limit is set to 0, the MSMI will work as before, that is, no size limits will be imposed.

If this registry value is being used, then a message with a header size that is larger than the header size limit will be returned to the sender. An error message is logged in the event log with event ID 2604. This event message gives the address of the sender and the MsgID of the returned message.

Additional query words: msmi header msmail ndr

Keywords : exc55sp2fix XFOR
Version : WinNT:5.5
Platform : winnt
Issue type : kbbug