You may have seen or intensified by fact that Outlook won’t permit you to open or save particular types of file attachments from email. Microsoft did this to attempt and avoids spread of viruses through email messages.

Microsoft came with an Outlook Email Security Update for Outlook 98 and 2000 which helps to block viruses by blocking certain attachments. This update is also included into Office 2000 Service Pack 2. New editions of Outlook have this built into program itself.

You can do a registry edit for Outlook 2000 SP3, 2002, 2003 and 2007 that will permit you to get access to blocked attachments in Outlook. Before doing any registry editing ensure to create a backup of registry.

Go to Start, Run and type in regedit and click Ok. Browse to following key.
HKEY_CURRENT_USER\Software\Microsoft\Office\10.0\O utlook\Security

Below that key, include a new string value called Level1Remove. You can do this by right clicking in a blank spot and selecting New-String Value and type Level1Remove for name. Then right tick new string and select Modify and enter a list of file extensions you want to permit divided by semicolons. E.g. you can add: .exe;.vbs;.mdb (without spaces) to add those file types to be permitted.

Once you apply this registry fix but still you have to save attached file to hard drive before opening it.