E-mail is one of the biggest threats（威胁）to your home computer. By understanding how E-mail works, and by
taking some steps in how you deal with reading and writing messages, you can keep this threat out of your computer. When you exchange E-mail with someone else, the messages sent between you and that person pass through several computers before they reach their places. Imagine this conversation as it is taking place in an Internet “room”, a very, very big room. Anyone, or more exactly, any program can probably understand what is being said, because most Internet conversations are not hidden（隐藏）in any way. As a result, others may be listening in, capturing what you send, and using it for their own good.
E-mail-borne viruses（病毒）often arrive in attractive, fantastic appearances, much like the beautiful ads we receive by way of traditional mail that is made to sell us something. By beautiful appearances, an infected（ 感染） E-mail message seems to be something we want to read from someone we know, not a mean virus ready to destroy or damage our computers.
There are some steps that you can take to help you decide what to do with every E-mail message with an attachment
（附件）that you receive. You should only read a message that passes all of these tests:

1）The Know Test: Is the E-mail from someone that you know?
2）The Received Test: Have you received E-mail from this sender before?
3）The Expect Test: Were you waiting for E-mail with an attachment from this sender?
4）The Meaning Test: Do the topic line of the E-mail massage and the name of the attachment both have meanings? 5）The Virus Test: Is the E-mail infected?
The passage is mainly talking about The Safety of Home Computers.

A.T

B.F