Microsoft has announced there is a security problem with the Macintosh Outlook Express 5.0 package. This security bug can leave users of the email software vulnerable to attacks by Trojan Horse viruses.

Warnings put out on the company’s behalf state: "OE 5 users should ensure they do NOT open any file in their Downloads Folder without knowing where the file came from." The security gap makes it possible for the maliciously-minded to send files to OE 5.0 that might have the ability to execute actions such as downloading files to a users default Download file. It appears files transferred in this way need to be opened before damage occurs.

The best advice seems to be: never open a file in the default downloads folder that you don’t recognize. The company said it is taking the issue very seriously, and is working on a fix.