As the Internet has become more and more popular, it has also become the venue of choice for some people with malicious intentions. Merlyn® wants to do everything he can to offer our clients a safe environment in which to work.

One of the more popular types of attacks people with nothing better to do like to perpetrate on the Web is to send attachments via e-mail that contain viruses, Trojan Horses, or other types of malicious scripts. In order to help keep your computer safer from such attack, we have implemented virus filters and have further extended this to prevent certain file extensions from passing through the mail server. Those file extensions are listed below:

.ade, .adp, .bas, .bat, .chm, .cmd, .com, .cpl, .crt, .eml, .exe, .hlp, .hta, .inf, .ins, .isp, .jse, .lnk, .mdb, .mde, .msc, .msi, .msp, .pcd, .reg, .scr, .sct, .shs, .url, .vbs, .vbe, .wsf, .wsh, .wsc

Some may think the list is a bit aggressive, but Merlyn® prefers to err on the side of caution.

This is not a foolproof method for preventing the spread of malicious programs. However, archiving files into a Zip file before attaching the files to an e-mail, forces the recipient to think twice before executing the contents of the file. If the recipient is expecting to receive an attachment from the sender, he will unzip the file's contents to view the information. If, however, the recipient is aware that many viruses spread by appearing to be from someone the recipient might know, then if the recipient is not expecting to receive an attachment from someone and one appears in his mailbox, the extra step he must take to unzip the file might give the him time to think better of performing the task and, thus, keep from executing malicious code on his computer.

This guide details how to create a Zip archive of the files to be sent via e-mail. The files do not have to be contained in a Zip file, you can use any compression algorithm. Zip is a popular archiving algorithm and is found on many computers which is why it is suggested. You will need a Zip archiver to be able to compress and decompress Zip files. One of the most popular Zip archivers for Windows is WinZip. You may read more about WinZip and download it at:

WinZip.com

Creating a Zip Archive

To create a Zip archive, locate the file you wish to archive by navigating through your computer system. You can use the My Computer icon to find the files on your hard drive to add to the archive.

In this example, demo.exe will be archived. Select the file to be archived. If multiple files are desired, hold down the Ctrl key while clicking the filenames. Once the file or files are selected, click on File --> WinZip --> Add to.... The archive name will be the same as the file being archived. Replace the current file extension with a .zip extension, as illustrated below.

After clicking Add to demo.zip, a file entitled demo.zip will appear in the same directory.

In your e-mail client, navigate to the directory and attach the Zip file to the message.

Decompressing a Zip File

To decompress a Zip file, save the attachment somewhere on your hard drive, navigate to this directory in the same manner as above, using My Computer.

Double clicking on the Zip file will open WinZip (assuming WinZip is installed on the computer). WinZip will reveal the contents of the Zip archive.

Click on Actions --> Extract...

In the dialog box, select the directory to extract the file into, in this example C:\Demos. The path may be entered in the text box or it may be selected with the directory structure.

Click Extract and the contents will be extracted to this directory. My Computer may also be used to navigate to the directory the contents were extracted to where the file's contents will be revealed.

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