I'm receiving attachments in emails that are either spyware or
messages encrypted into another file.  Often the place a fake
extension on it so that when I open it OS X opens it in the wrong
format and destroys the data or message. INFO doesn't work.

How can I determine the actual file type?

Uhm...I think this should work. Open up a console terminal. Go to the
directory where the file is located and type "file <filename>" and it
will tell you what kind of file it is (executeable, text, image,
etc.).

how do I go to a directory in terminal?

first of all if you want to be asured of file extension on windows
then you need to goto Folder options in the Control panel, select View
tab, and just below the "Hidde Files" section, there is also a
checkbox for Hide extension for known file types. Remove check box
from here.

This will solve your general extension problem in windows. Usually
since known file type's extensions are invisible, people make icons
similar to images and send viruses and you consider it to be image and
you open it and then it turns out to be virus.

Next thing you can do is, goto outlook express's tools menu, click on
options. Click on security tab. Check the box of "Do not allow
attensions to open or saved that potentially could be virus" this
disabled exe kind of attachments.

Apart from this, you can tell mail administrator of your email service
to set filter for such file extensions. It is possible in all sort of
latest email servers.

Beyond this there is no other way, I have built mail server and we are
providing IMAP/POP3 email services to existing as well as new users,
you also can signup freely at our website at evenmail.com we are
experts in email system organization.

- Akash Kava

Yes,it maybe difficult to determine the file type. Because it just virus