To manually enable or disable the PDF File Preview integration within Microsoft Outlook, please follow the instructions below:
Within Microsoft Outlook 2010, go to "File" menu and click "Options".
Select the "Trust Center" link.
Click on the "Trust Center Settings..." button.
Select the "Attachment Handling" menu.
Click on the "Attachment and Document Previewers..." button.
Locate the "zeon PDF PreviewHandler" option from the "File Previewing Options" list.
To enable the PDF File Preview option, place a check in the "zeon PDF PreviewHandler" checkbox.
Note: To disable the PDF File Preview option, remove the check from the "zeon PDF PreviewHandler" checkbox.
Click "OK" to apply the changes.
Note: The "zeon PDF PreviewHandler" File Previewing Option may also be listed as "Nuance PDF PreviewHandler".