Outlook 2010 PDF preview not working

Internet Explorer -> Tools -> Internet Options - Connections tab - LAN settings - Uncheck "Automatically detect settings"

Close IE, close outlook and go back into outlook.

I don't know why this works.

Hi regar brians

Could you please check if PDF preview is enabled under Reader's preferences- launch Reader > click Edit > Preferences > General > check the box next to "Enable PDF thumbnail previews in Windows Explorer" > click OK and try again.

Make Adobe Reader DC as a default PDF viewer for PDF files using the steps given in the links below:

https://support.microsoft.com/en-us/help/18539/windows-7-change-default-programs

Associate PDF files to always open in Acrobat or Reader on Windows 10

Also, enable PDF Preview handler in Outlook if you haven't already following the steps given here: Preview Handler Error in Outlook 2013

Reboot the machine and check.

Thanks,

Shivam

Hi har52513472,

As you experiencing a problem with PDF preview handler, please let us know the application you are using to view the PDF.

If you are using Adobe application, could you please try the steps provided here on these thread with the similar issue:

Adobe PDF preview handler error after install Reader XI

MS Outlook - Problem with Adobe PDF Preview Handler (Review and Comment) 

Could you please share the dot version of the Adobe application and OS installed on your system.

Also, share the screenshot of the exact error message you get.

Regards,

Meenakshi