Many worm vira makes use of OE to email the vira to everyone in the address book.
Instead of using HTML as the default email format, then change it to use Plain Text.
To configure OE go to the menu "Tools" and select "Options..."
select the fan "Send" and set the following :
- Untick "Reply to message using the format in which they were sent"
- "Mail Sending Format" is to be set to "Plain Text"
In case one need to send an email with HTML then one can change this for the new email
by selecting "Format" in the menu for the window containing the new mail and
change it to "Rich Text(HTML)".
More Info MS KB291387