Background: Some user may meet "The file cannot be previewed because there is no previewer installed for it in Outlook" when using outlook like below picture.
Here is the solution:
1) Open Foxit Editor > File > Preferences >File Associations >Disable "Include preview when setting default PDF Viewer" then click to confirm.
2) In File Association > Click "Make default PDF Viewer" then click to confirm.
3) Back to Foxit Editor > File > Preferences >File Associations >Enable ""Include preview when setting default PDF Viewer"" then click to confirm.
4) In File Association > Click "Make default PDF Viewer" then click to confirm. Then you could see if outlook could preview PDF normally.