A comment about "preview windows" in email clients (Eudora, Outlook,
etc)..... if you have the preview window enabled, the client has to
render (executing anything allowed, in the process) whatever HTML might
be in the message to populate the preview. By the time you decide the
message is Something Bad, its too late.

Bottom line is that a preview window is a security risk. Be aware of
what is allowed to execute (Active X, Java, whatever,) and take
appropriate precautions if you use this feature.
Randy