KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q269439: XADM: Synchronization of .ost Files Won’t Work w. Antivirus API

Article: Q269439
Product(s): Microsoft Exchange
Version(s): 5.5 SP3
Operating System(s): 
Keyword(s): exc55sp3
Last Modified: 22-JUL-2002

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft Exchange Server, version 5.5 SP3 
-------------------------------------------------------------------------------

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:

  Q256986 Description of the Microsoft Windows Registry

SYMPTOMS
========

If Exchange clients attempt to synchronize the .ost files when third-party
software that uses the new antivirus application programming interface (API) is
installed on the Exchange Server computer, the clients may experience slow
synchronization, synchronization time-outs, or inability to complete the
synchronization process.

CAUSE
=====

This issue can occur because when the antivirus API is in use, each message that
contains an attachment must be scanned before the message is released to a
client by the Exchange Server information store. If the scanning queue contains
messages that contain many attachments or several large attachments, the client
may time out while it waits for the server to release the message that contains
the attachment.

RESOLUTION
==========

To determine whether you are experiencing the issue that is described in this
article, disable the antivirus API by either disabling the third-party software
or changing the Enable value in the registry. To change the Enable value, you
need to edit the registry:

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.

WARNING: When you disable the antivirus API and subsequently re-enable the
antivirus API, all attachments are resubmitted to the third-party software to be
scanned.

1. Start Registry Editor (Regedt32.exe).

2. Locate the Enabled value under the following key in the registry:

  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\VirusScan

3. On the Edit menu, click DWORD, type "0" (without the quotation marks), and
  then click OK.

4. Quit Registry Editor.

After you change the Enabled value, allow up to two minutes for the change to
take effect, and then test .ost synchronization.

If .ost synchronization finishes normally, re-enabled the antivirus API by
changing the Enabled value back to "1" (without the quotation marks).

Although the performance of the antivirus API is bound by the third-party
software implementation, you can add or change the OpenRetryDelay value in the
registry to try to resolve this issue. This value is the time interval in
milliseconds that the information store pauses before it attempts to reopen
attachments that are currently being scanned when those attachments are
requested by the client. If you set this value too high, you may cause client
time-outs, and if you set this value too low, you may cause additional
processing overhead by the information store. If this value is not present in
the registry when the antivirus API is in use, it has a hard-coded default value
of 500 milliseconds.

IMPORTANT: Although the following procedure uses a value of 250 milliseconds,
this value may not be the correct value in every case. Choose this value based
upon your particular environment.

1. Start Registry Editor (Regedt32.exe).

2. Locate the following key in the registry:

  HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\VirusScan

If the VirusScan key is not present, the antivirus API is not in use or has never
been enabled on the Exchange Server computer.

3. Locate the OpenRetryDelay value under the preceding key in the registry. If
  the OpenRetryDelay value is not present, go directly to step 5.

4. On the Edit menu, click DWORD, type "250" (without the quotation marks),
  select a Radix of Decimal, and then click OK.

5. If the OpenRetryDelay value is not present, add it; on the Edit menu, click
  Add Value, and then add the following registry value:

  Value Name: OpenRetryDelay
  Data Type: REG_DWORD
  Radix: Decimal
  Value: 250

6. Quit Registry Editor.

7. Restart the information store service to make the changes take effect.

If you do not notice any improvement after you change this value, contact the
third-party software representative for assistance in further improving
performance of the antivirus scanning process.

Additional query words: Anti-Virus AVAPI Sync timeout vapi

======================================================================
Keywords          : exc55sp3 
Technology        : kbExchangeSearch kbZNotKeyword2 kbExchange550SP3
Version           : :5.5 SP3
Issue type        : kbprb

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.