Avoiding Windows email viruses with Mozilla Mail

By Phil Jones and Vidar Braut Haarr, October 2005

"The users that I support would double-click on a landmine to see what it did." -- slashdot.org

Summary

To avoid the "email viruses" that target your Microsoft Windows based computer:

Install Mozilla Mail (it is free).
Read this article carefully (it will pay off).
Stop worrying.
But, be cautious with unknown archive files received as attachments (such as ".zip" files).
Beware of Microsoft Office formatted document files received by email (they can carry viruses).
Finally, be sure to keep up with the latest version of Mozilla Internet Suite.

About this article

We all love email. But email is also a problem. There are "pests" that spread from one computer to another, by email. It is a bit like a chain letter, but computerised and spreads at astonishing speed. These pests can do serious damage, such as haunt you with massive phone bills, sudden slow downs, random crashes, and so on.

The marvellous Mozilla team have done a fine job with Mozilla Mail. It helps you:

Enjoy using Internet email.
Keep email-bourne pests out of your computer.
Reduce the need for so-called "anti-virus" software.

The information in this article is for beginners using Mozilla Mail on the Microsoft Windows operating system. This article assumes that you already have Mozilla installed and set up, perhaps by a friend or by a computer engineer. Mozilla Mail (full title Mozilla Mail & Newsgroups) is the email component of the Mozilla Internet Suite application. Mozilla Thunderbird is the email component as a standalone application.

How Mozilla Mail protects you

It helps prevent accidents when you are dealing with your email.
It helps you spot harmful attachments, by giving you full details ahead of time.
It is immune to email viruses that try to automatically run when you view a message.
It is immune to email viruses that hide inside picture (image) files.

Phil's three-line guide to spotting email viruses

Is there an attachment with a name that ends in ".zip"?

OR
When you click on an attachment, do you get only two options rather than the usual three?

Examples

A ".zip" attachment

The message below has an attachment with a name ending in ".zip". The dot and last three letter is called the extension. The extension tells the computer what sort of file it is. A ".zip" file is a compressed file which contains more files. If you receive a message like this, just delete it (unless you are expecting it and you know what it is about).

Zip attachment

An ".exe" attachment

The message below has an attachment with an ".exe" extension. The ".exe" extension means "executable" or "program". If you receive a message like this, just delete it.

Bearr virus

A ".pif" attachment

The message below has an attachment with a ".pif" extension. The ".pif" extension means it is a program, like ".exe". If you receive a message like this, just delete it. The other most common virus extension to watch out for is ".scr", which means screensaver.

Petite virus

Opening attachments

Sometimes, Mozilla Mail will ask you what to do with an attachment. Usually there are three options, the first being "Open it with the default application" and this is usually nothing to worry about. Simply click OK and the attachment will be opened.

Now, this is the important part. When you are dealing with a potentially dangerous sort of attachment, you only get two options, "Open it with" and "Save it to disk". This helps protect against accidents, because it means you have to think about what you are doing. If you are unsure, click Cancel and no harm will come to your computer.

Opening Your Stuff

Review

If you double-click on an attachment...

...and it is a Zip file, and you don't know who it is from, or what it is about, click Cancel, then delete the message.
...if it is any other type of file, and you only get two options instead of the usual three, click Cancel, then delete the message.

Limitations

Mozilla Mail gives "anti-virus" software less to do. But there are still problems that you should know about.

Microsoft Word/Excel/Powerpoint/Access files

Remember when you couldn't get a virus from reading a word-processed file? Microsoft made it possible. In Microsoft Office 97, and later, Word / Excel / Powerpoint / Access document files may have their own viruses hidden inside. For example, if you receive an infected ".doc" file by email, Mozilla Mail will cheerfully pass the file to Word. Unfortunate problems may ensue. An effective defence is to use the free OpenOffice.org instead of Microsoft Office, since OpenOffice.org ignores Microsoft Office viruses.

Joint Picture Experts Group (JPEG) images

Remember when you couldn't get a virus from looking at a picture? Microsoft has made that possible, too. Simply viewing a JPEG format image could now give you a virus. Unfortunately this is a complicated problem. The best advice is to look at the Microsoft article on the subject. Fortunately, poisoned JPEG format images have no effect on Mozilla.

Weaknesses within Mozilla Mail itself

Mozilla Mail is not perfect (sorry). A virus could (theoretically) take advantage of known vulnerabilities in Mozilla to target Mozilla Mail users. So, make sure you are running the latest version of Mozilla (currently version 1.7.12). All the publically known weaknesses are fixed in the latest version.

Deep inside the old Netscape code upon which Mozilla Mail is based, there are probably plenty more skeletons waiting to be discovered. So our advice is: check occasionally for new versions and keep up to date. Fortunately, Mozilla Mail is very easy to update. Simply download the Mozilla Internet Suite installer and run it. It will install the new version over the top of the old one, keeping your settings, mail and address books in place.

Part 2: Other things you can do to improve Mozilla Mail's privacy and security