PC MAPI: Loss of Memory with MapiSendMail and Visual Basic (148369)
The information in this article applies to:
- Microsoft Mail for Windows 3.5
This article was previously published under Q148369 SYMPTOMS
When the MAPI function MAPISendMail is used in an application developed
with Microsoft Visual Basic versions 2.0 and 3.0 for Windows, the memory is
not released properly from the global heap. When you exit the MAPI
application, it will release the memory.
If the application sends large numbers of messages or several messages with
multiple recipients the heap memory could be exhausted and result in
subsequent failures of applications running in the Microsoft Windows
environment.
When the MAPI application is stopped, the memory that was not released
during operation will be released and become available to other
applications.
The amount of memory lost during the MAPISendMail function call will be on
the order of 32 bytes for each recipient and 32 bytes for each attached
file. If the Windows system has a few megabytes of available memory, it
will take thousands of messages to exhaust the heap. This is a problem only
for a program designed to run for long continuous periods.
CAUSE
The loss of heap memory is a result of an error in MAPI.DLL and the way it
frees allocated memory. The memory fails to be released for each recipient
and for each attached file in the message. This loss only occurs when the
Visual Basic MAPI interface is used. It does not occur if the application
uses the MAPI interface for Microsoft C.
STATUS
Microsoft has confirmed this to be a problem in version 3.5 of Microsoft
Mail for Windows. A fix for this problem is in development, but has not
been regression-tested and may be destabilizing in production environments.
Contact Microsoft Product Support Services for more information on the
availability of this fix.
| Modification Type: | Major | Last Reviewed: | 1/23/2000 |
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| Keywords: | KB148369 |
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