In Microsoft Outlook 2000, XP (2002), 2003, and Outlook 2007 from the Microsoft Office 2007 or later, when attempting to open an attachment that came with an email, a dialog box will prompt for options that ask whether you like to open the file or save it to computer. Other than allowing users to choose which action user want to Outlook to perform, the dialog also has a check box of “Always ask before opening this type of file” setting, which if untick or clear, will make the choice permanent and Outlook always does the selected action by default for the type and extension of attachment file in the future without prompting again.

If you have accidentally unchecked the check box, or for whatever reason want to reset or revert the “Always ask before opening this type of file” setting so that Office Outlook will return change back to the default behavior with prompt to save or open functionality, we can use the same trick as reset the always ask setting in IE. The same trick will work because the “Always Ask Before Opening This Type of File” setting is actually an operating system variable, and both IE and Outlook use it to determine the action needed to perform.

To recap, follow this steps to reset the behavior so that Outlook will prompt you to open or save the file type:

  1. Open the Control Panel Folder Options applet or open it from Tools -> Folder Options in any Explorer window.
  2. Select the File Types tab.
  3. Scroll down to the extension type that you want to reset.
  4. Select the extension type, then click Advanced.
  5. Check the “Confirm open after download” check box, then click OK.
  6. Click Close to the Folder Options dialog box.

Note: The trick works in Outlook installed in Windows XP or earlier OS.