Policy

Remove file extensions blocked as Level 1

This policy setting controls which types of attachments (determined by file extension) Outlook prevents from being delivered. Outlook uses two levels of security to restrict user's access to files attached to e-mail messages or other items. Files with specific extensions can be categorized as Level 1 (users cannot view the file) or Level 2 (users can open the file after saving it to disk). Users can freely open files of types that are not categorized as Level 1 or Level 2. If you enable this policy setting, you can specify the removal of file type extensions that Outlook classifies as Level 1 (that is, to be blocked from delivery) entering them in the text field provided separated by semicolons. If you disable or do not configure this policy setting, Outlook classifies a number of potentially harmful file types (such as those with .exe, .reg, and .vbs extensions) as Level 1 and blocks files with those extensions from being delivered. Important: This policy setting only applies if the "Outlook Security Mode" policy setting under "Microsoft Outlook 2016\Security\Security Form Settings" is configured to "Use Outlook Security Group Policy."

Policy
Pack Microsoft Office
Category Microsoft Outlook 2016 / Security / Security Form Settings / Attachment Security
Policy ID 8825c6933c93
Internal name L_Level1RemoveFilePolicy

Registry

Copy registry mappings

HKCU\software\policies\microsoft\office\16.0\outlook\security\fileextensionsremovelevel1

Policy notes

This policy setting controls which types of attachments (determined by file extension) Outlook prevents from being delivered. Outlook uses two levels of security to restrict user's access to files attached to e-mail messages or other items. Files with specific extensions can be categorized as Level 1 (users cannot view the file) or Level 2 (users can open the file after saving it to disk). Users can freely open files of types that are not categorized as Level 1 or Level 2. If you enable this policy setting, you can specify the removal of file type extensions that Outlook classifies as Level 1 (that is, to be blocked from delivery) entering them in the text field provided separated by semicolons. If you disable or do not configure this policy setting, Outlook classifies a number of potentially harmful file types (such as those with .exe, .reg, and .vbs extensions) as Level 1 and blocks files with those extensions from being delivered. Important: This policy setting only applies if the "Outlook Security Mode" policy setting under "Microsoft Outlook 2016\Security\Security Form Settings" is configured to "Use Outlook Security Group Policy."

Related policies

Add file extensions to block as Level 1Add file extensions to block as Level 2Allow users to demote attachments to Level 2Display Level 1 attachmentsDisplay OLE package objectsDo not prompt about Level 1 attachments when closing an itemDo not prompt about Level 1 attachments when sending an item