Email has become part of the very fabric of our lives. It lets us communicate quickly and easily with friends and family across town or across the globe. But do not let email's convenience make you forget about its potential dangers.

Following a few simple guidelines when using email can help protect you and your computer from identity thieves and unscrupulous businesses.

Treat email like a postcard: Email is not a private method of communication. Anyone with a certain level of technological know-how can read what you send. While it may seem unlikely that anyone would bother trying to read your emails in transit, it is wise to err on the side of caution.

Avoid writing anything in an email that you would not be willing to write on a postcard and drop in a mailbox. That means no personal financial information like account numbers, Social Security numbers, or passwords.

Avoiding email viruses: Hardly a week goes by without a major news story about a virus circulating on the Internet by email. These viruses typically arrive in the form of an attachment with some enticing invitation to open it.

If you open it, the virus can do almost anything—from sending out copies of itself to everyone in your address book to crashing your computer completely. Your best bet is to delete the email and the attachment immediately without opening them, especially if you don't know the sender.

Viruses are tricky though, and the emails they are attached to can seem to be from someone you know and trust, someone who would never knowingly send you a computer virus. So, it pays to be suspicious of attachments in general.

Before you open an unexpected attachment from a friend or family member, you may want to send them an email or give them a call to make sure they sent it.

Dealing with spam: Unsolicited email—commonly called spam—is a growing problem on the Internet, both for recipients and for companies trying to use email to communicate with customers. Low mortgage rate offers, porn site solicitations, phishing scams and ads for merchandise are all forms of spam.

Use a spam filter: A good first line of defense against spam is spam-blocking software. Many email programs like Outlook and Eudora have built-in spam protection tools. Likewise, your Internet service provider may include a spam-blocking system bundled with their service. If these options are not available to you, look into purchasing and installing spam-blocking software for yourself. These systems do a reasonable job of reducing spam, but they are not 100% effective.

Delete without opening: When you reply or even open a spam message you may be confirming to the spammer that your email address is active. That's likely to mean more spam will be coming your way as the "good" address gets passed around among spammers.

Unsubscribe with caution: If spam comes from a company or individual you don't know, following the instructions to "unsubscribe" or be removed from the mailing list is not likely to stop the spam. Your request will probably just confirm to the spammer that the address is active, and your address is more likely to be added to other lists rather than removed from any.

However, if what you think of as spam is coming from a company you have a relationship with, consider the possibility that they think you want to receive what they are sending. They might not realize they are annoying you with these emails because you may have forgotten you signed up for a newsletter or special offers by email. Legitimate businesses that want you as a customer will generally provide you with an email address to contact them to have your name removed from email lists.

Report spammers: Internet service providers often make ongoing efforts to combat spam on their systems. By reporting spam when you receive it, you can sometimes help service providers thwart spammers in the future. Contact your provider to find out if they have procedures in place for you to report spam.

A virus or spyware on your computer can do more than just crash your system or delete files. More insidious strains can present a serious threat to the security of personal information.

A virus is a program that enters your computer without your knowledge and attaches itself to other files, replicating itself and spreading. Spyware is similar in that it invades your computer without your knowledge, but it also monitors your activity. In some cases it may report this activity back to the person who originally wrote the program.

Keeping your computer free of all unwanted programs is an important aspect of making sure your personal information is secure.

Be cautious when downloading: Be aware that whenever you download software or application files from the Internet, you could be allowing a Trojan horse into your system. A Trojan horse is a file that has undesired components like viruses or spyware hidden inside.

These programs vary in the amount of damage they do. One might simply annoy and frustrate you by resetting your browser's home page and not letting you change it back. Another might capture your ID and password as you log into a financial site and then relay that information back to the source, where it may be used to steal your identity.

Be as certain as possible that you can trust the integrity of the source before downloading anything.

However, you don't have to download something for malicious programs to find their way onto your system. Some of them can sneak onto your computer without any action on your part beyond visiting a website that hasn't taken appropriate steps to prevent hackers from triggering these "drive-by" downloads. Our site has security measures in place to combat this kind of activity.

Keeping your system clean: Antivirus and antispyware programs that seek out and destroy spyware are available to help keep such programs off your system. But be aware that viruses and spyware are not easy to eliminate.

For instance, spyware programs typically hit your computer in clusters rather than single programs. So when spyware A invades your machine, spyware B, C, D and E may also sneak in and find a place to hide. In addition to watching you, these programs watch each other. If spyware A gets deleted, spyware B reaches out to the originator and grabs another copy. So it is important to be disconnected from the Internet before trying to clean these files from your system.

Our Internet security expert recommends running your antispyware and antivirus programs several times in succession. Each run may be able to peel off layers of "masks," allowing the programs to work in tandem to target and destroy spyware and viruses that have been hiding. As a final step, restart your computer. Then run your antispyware and antivirus programs once more.

This process may seem like overkill, but many experts believe it is worth the effort to keep your system clean. If you had rather not do all of what's described above, it is a good idea to run the antispyware and antivirus programs at least once.

While airports and other venues with public computer terminals offer convenience, using them could compromise the security of your personal information.

You are on a vacation and have not been able to check your emails for a week. You stop for a cappuccino and notice a computer terminal in the corner of the coffee shop. It has Internet access, and you decide to check your email and glance at the headlines on your favorite news website. No problem so far.

Then you decide to visit your bank's website, log in and check to see if a couple of recent transactions have cleared. Is that a good idea? Probably not since you are using a public computer terminal.

There is no way for you to know what kinds of spyware programs are installed on public terminals. The computer may contain key tracking software or other invasive programs installed by someone who used the terminal previously. Those programs could help someone steal your identity if you are typing in personal information like an ID and password for online access to your bank account.

Given the ease with which spyware and other treacherous programs can imbed themselves on a personal computer used only by you, it is wise to be extra cautious and never access personal financial data from a computer used by the general public.

Certain information and statements made herein have been derived by third party sources. While we consider that information to be reliable, we give no assurance that such information or statements are accurate or complete.