Detail
To test that your Virus Checker plug-in and anti-virus software is working, first temporarily disable the auto-protect feature of your antivirus software. Then visit the following site to download a test virus:
http://www.eicar.org/anti_virus_test_file.htm.
Specifically download the file eicar.com. Then, attach this file to an e-mail message and send it through WorkgroupMail. If you send it to an external recipient, it should get caught in the Outgoing Quarantine folder. If this happens, then the VirusChecker plug-in is correctly configured.