Why can't I open a "zip" or other attachment? The latest generation of e-mail viruses use .zip files among other type of executables to spread the virus to other machines. These viruses spread rapidly worldwide infecting millions of computers. Compounding this problem, the virus creators launched many variants in rapid succession. Because of the speed with which these viruses spread and the number of variants, the anti-virus software vendors couldn't release updates to stop these viruses quickly enough. As a result some state PC were infected, causing these viruses to spread within the state network.

Because of these developments, the decision was made to block all attachment types that e-mail viruses are known to propagate with. Of all attachments being blocked, the .zip is the most commonly used by e-mail users.

As a work around DoIT recommends the following. The sender should create the file with the .zip extension as usual. Then they should RENAME the file extension to something other then .zip (like .zix), then attach the file to the message. The recipient should save attachment to their PC then rename the file extension back to .zip. The other extensions that are currently being blocked are .pif, .scr, .bat, .cmd, .exe, .com, .rar, .cpl, .hta