Microsoft® Office 2003 Editions Resource Kit

Attachment File Types Restricted by Outlook 2003

By default, access is restricted to certain e-mail message attachments in Microsoft Outlook. In determining which attachments are blocked, Outlook checks the file type of the attachment. Files with certain file types can be completely blocked (Level1) or the user may be required to save a file to disk before opening the file (Level 2).

By default, Outlook classifies a number of file type extensions as Level 1 and blocks files with those extensions from being received the users. There are no Level 2 file types by default, but you can create a list of Level 2 file types by using the Outlook Security template. You can demote file types from being categorized as Level 1 to being Level 2, or you can ...