Hi, DLfromga!
Thanks for reaching Microsoft Community. We are sorry to learn you are having troubles previewing PDF files in Outlook and I understand it takes time to save the file in order to view it.
Based on the Preview attachments in Outlook page, Outlook doesn't include a built-in PDF previewer. In order to preview PDF files, use the following steps.
- Close Outlook
- Download and install Adobe Acrobat Reader
- Make Adobe Acrobat Reader the default program used to open PDF file.
- Refer to this page on how you can change default programs in Windows 10
- Restart Outlook.
If this works, we highly encourage you to inform our Community by clicking on Yes or marking my post as an answer. This will help other members who may have the same issue as you. Otherwise, don't hesitate to update us so we can further assist you.
Kind regards,
Janette_Z