Configuring Outlook To Block Additional File Types
For many years, Microsoft Outlook has blocked certain attachment types — usually executable or psuedo-executable — for reasons of safety, while allowing others, such as document files and others such as ZIP archives which are typically not used in malware distribution.
However, ZIP files are being used increasingly to distribute malware via email because ZIP files are not typically blocked, and modern versions of Windows (from Windows XP) are able to open them easily. Thus it can be desirable to disable access to such files. If users need to transfer ZIP or other files, services such as DropBox make this much simpler and more efficient anyway.
To block, say, ZIP and RAR files in various versions of Outlook, use the following commands either at the prompt or in a login script:
reg add HKCU\Software\Microsoft\Office\<n>\Outlook\Security /v Level1Add /d ".zip;.rar;" /t REG_SZ /f
(<n> is the version of Office installed.)