I have had this email a few times now. If you get it do not open the attachment, delete it.
Dear user of "COM.AU" mailing system,
Our antivirus software has detected a large ammount of viruses outgoing from your email account, you may use our free anti-virus tool to clean up your computer software.
For more information see the attached file.
Attached file protected with the password for security reasons. Password is 10745.
