Exchange Virus Scanning API compatible product was detected, but it is not correctly installed

[This topic is intended to address a specific issue called out by the Exchange Server Analyzer Tool. You should apply it only to systems that have had the Exchange Server Analyzer Tool run against them and are experiencing that specific issue. The Exchange Server Analyzer Tool, available as a free download, remotely collects configuration data from each server in the topology and automatically analyzes the data. The resulting report details important configuration issues, potential problems, and nondefault product settings. By following these recommendations, you can achieve better performance, scalability, reliability, and uptime. For more information about the tool or to download the latest versions, see "Microsoft Exchange Analyzers" at]  

Topic Last Modified: 2005-11-18

The Microsoft® Exchange Server Analyzer Tool reads the following registry entry to determine whether Virus Scanning Application Programming Interface (VSAPI)-compliant software is running on the computer and has a valid library referenced:


If the Exchange Server Analyzer finds the value for Library does not contain a valid path to a VSAPI antivirus library file (DLL), a warning is displayed.

It is generally recommended that you deploy antivirus software designed for messaging systems at the Simple Mail Transfer Protocol (SMTP) gateway or on the Exchange Server computers that host mailboxes. For the most protection, run antivirus software at the gateway that scans the inbound MIME messages and a scanner on the Exchange Server computer that uses VSAPI 2.0 (Exchange 2000 Server) or VSAPI 2.5 (Exchange Server 2003).

In addition, you should run antivirus software on the client computers. If you run antivirus software designed for messaging systems (meaning that it can parse and scan MIME) at the gateway or on the Exchange server, running a file-level scanner on the client computers is sufficient.

To correct this warning

  1. Uninstall and then reinstall the antivirus software.

  2. If the problem persists after you reinstall the software, contact your antivirus software vendor for assistance.

For more information about virus-scanning programs that are typically used with Microsoft Exchange Server 2003, see the Microsoft Knowledge Base article 823166, "Overview of Exchange Server 2003 and antivirus software" (

For more information about virus-scanning programs that are typically used with Microsoft Exchange 2000 Server, see the Knowledge Base article 328841, "Exchange and Antivirus Software" (

For more information about fortifying an Exchange environment against e-mail transmitted viruses and worms, see "Slowing and Stopping E-Mail Viruses in an Exchange Server 2003 Environment" (