Computer Malware and Zombie Computers

It is possible for some types of email to carry computer malware to your Subscribers.

If your Email Discussion Group is run with the default settings, that will never happen at

What does malware do?

A virus computer program or malware can damage your personal computer by deleting or corrupting files on your hard disk. It can also silently intercept your keystrokes, and capture the passwords to accounts like  online banking.

Other variations of these destructive programs are called Trojan horse and Computer Worm.

What are "Zombie" computers?

Computer malware will allow somebody else to remotely control the computer. The owner of the computer is rarely aware of the problem, and thus these computers are called zombies. It is estimated that millions of Windows computers in the United States have been taken over and are secretly under the control of somebody else. Among other problems, this is a big national security risk.

Currently, the most common action taken is to send out Spam, especially to email addresses of contacts found on your computer. Some of the emails contain the same Trojan horse as an attachment, thus spreading the problem.

Can attachments and HTML carry malware?

Yes. Computer malware can be spread via attachments. We have experienced viruses in PDFs, MS Word documents, executable programs, Flash videos, pictures, music, and about any other file type you can think of. The computer virus scanners currently know more than 1 million different computer viruses. Although, the number of viruses found actively circulating is much smaller.

Computer malware can also be spread in HTML email, because HTML has a feature that allows small programs to be downloaded and run on your computer. Java, Javascript and VBscript are examples of these types of languages. When you see rotating graphics, pop-up windows, and other fancy web page effects, it is typically small programs written in these languages that are doing the work. If the program was instead malware, bad things can happen to your computer.

HTML email can also allow linking to websites that contain the malware. The program was not downloaded inside the email, but brought in from the remote server. This type of malware is called cross-site scripting.

Plain Text Emails can save the world!

The only good news is that plain text email cannot be used, and never has been, to send a computer virus.  All of the email sent through has been converted to plain text email. We never send HTML email. If your Subscribers send messages in HTML, it is converted to plain text before being sent to your List.

  • For Announcement Lists, will remove any attachments, by default.
  • For Email Discussion Groups run in default mode, there is no chance that any email to your List will ever affect your Subscribers.

If you choose to allow attachments to your list, our system will scan these attachments with two different virus scanners, Clam-AV and Sophos. Therefore, even with attachments, there is a low risk of bad things happening to your Subscriber's computer.

Attachments can be converted to clickable links in your Mailing List email messages. To find out more about this option, please review the links below:

For Email Discussion Groups  -  Allowing attachments and clickable links

For Announcement Lists  -  Sending attachments as links