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Q159287: XCLN: MAPIFindNext Fails to Retrieve Message Identifiers

Article: Q159287
Product(s): Microsoft Exchange
Version(s): WINDOWS:4.0
Operating System(s): 
Keyword(s): kbusage
Last Modified: 12-APR-1999

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The information in this article applies to:

- Microsoft Exchange Windows 95/98 client, version 4.0 
- Microsoft Exchange Windows 3.x client, version 4.0 
- Microsoft Exchange Windows NT client, version 4.0 
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SYMPTOMS
========

Using the simple MAPI function MAPIFindNext in MAPI version 1.0 may fail to
retrieve the next (or first) message identifier of a specified type of incoming
message. The following is the resulting return code of the MAPIFindNext call:

     MAPI_E_NO_MESSAGES

CAUSE
=====

When you use MAPI version 1.0, choosing the value "IPM." for parameter
lpszMessageType in the MAPIFindNext function call does not retrieve the next
message identifier of the specified type (IPM) of incoming message. This value
has been used successfully in previous versions of simple MAPI to enumerate all
messages of a given message type.

WORKAROUND
==========

Instead of using "IPM." as value to enumerate messages of an IPM message type,
specify "NULL" (without the quotation marks) in the lpszMessageType parameter of
the MAPIFindNext function call.

STATUS
======

Microsoft has confirmed this to be a problem in the Microsoft Exchange clients,
version 4.0, listed at the beginning of this article. This problem was corrected
in Microsoft Exchange Server 4.0 U.S. Service Pack 4. For information on
obtaining the service pack, query on the following word in the Microsoft
Knowledge Base (without the spaces):

  S E R V P A C K

MORE INFORMATION
================

The MAPI SDK online documentation states the following regarding the
lpszMessageType parameter of the MAPIFindNext function:

  When the lpszSeedMessageID parameter is NULL or points to an empty string,
  MAPIFindNext returns the message identifier for the first message of the type
  specified by the lpszMessageType parameter. When lpszSeedMessageID contains a
  valid identifier, the function returns the next matching message of the type
  specified by lpszMessageType. Repeated calls to MAPIFindNext ultimately
  result in a return of the MAPI_E_NO_MESSAGES value, which means the
  enumeration is complete. Message type matching is done against message class
  strings. All message types whose names match (up to the length specified in
  lpszMessageType) are returned.

The last sentence implies that a message type string portion such as "IPM." or
"IPC." can be used with wildcard functionality to enumerate all messages of the
given message type. As a result, there are two methods for successfully
enumerating IPM type messages using simple MAPI:

- 

  ulResult = (*lpfnMAPIFindNext)(hMAPISession, hWnd, "IPM.",
     lpszSeedMessageID, flFlag, 0L, lpszMessageID);

- 

  ulResult = (*lpfnMAPIFindNext)(hMAPISession, hWnd, NULL,
     lpszSeedMessageID, flFlag, 0L, lpszMessageID);

Using MAPI version 1.0, only the second method successfully retrieves the next
(or first) message identifier of a specified type of incoming message. This
behavior would require changing the source codes for all applications using the
first method to enumerate IPM type messages, and recompiling them.


Installation
------------

This description uses the Microsoft Exchange Windows NT client, version 4.0 as an
example.

1. Close all applications that use Mapi32.dll

2. Back up Mapi32.dll from the <Winntroot>\System32 directory.

3. Copy the extracted version of Mapi32.dll to the <Winntroot>\System32
  directory.

4. Restart any applications that were stopped in step 1.

Additional query words: WIN32 SDK Simple Messaging 5.00

======================================================================
Keywords          : kbusage 
Technology        : kbExchangeSearch kbExchange400 kbExchangeClientSearch kbZNotKeyword kbZNotKeyword2 kbZNotKeyword3 kbExchange400NT kbExchange400Win95
Version           : WINDOWS:4.0
Issue type        : kbbug
Solution Type     : kbfix

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