Conditional Access App Control with PDF files

Question

Hi,

I have implemented Conditional Access App Control using Cloud App Security to set restrictions for download and copy/paste, when accessed from an unmanaged device. This works fine in the main, but I am having issues when viewing PDF's in Outlook on the Web. In Teams when I have a PDF file, I can click on the link and it will render in Teams as a viewable file. In Outlook Web it always tries to download the file, even when clicking on the Preview option in the attachment. Microsoft Office attachment files preview as normal but PDF's don't

I have tried multiple browsers and checked the settings to ensure that the files should open in the browser by default. but downloads every time, which is being blocked. I don;t really want to have to make an exception in the policy for PDF's 

Anyone else come across this issue and can suggest a fix? 

Movedfrom: (Microsoft 365 and Office | Outlook | Windows 10 | Microsoft 365 Family)

Answer 1

Hi,

Thanks for the info but as I mentioned in the question this is through the browser not the Outlook app (the same applies if I right click on a PDF n Teams and select open in browser although teams does render the PDF within the Teams editor).

The browsers I am using (and it is all) allow PDF's to open, so it is not tied to Adobe Reader.  

If I change the Cloud App Security policy to allow PDFs to download and then click on the preview option in Exchange Web the PDF does render, without downloading it, so there seems to be some requirement for PDFs to download a local copy even for displaying in preview, which is not the case for any Microsoft Office file

Answer 2

Hi AndrewR-SWW,

Thank you for choosing Microsoft community.

As far as I know, this might be due to that "Outlook doesn't include a built-in PDF previewer". See Preview attachments in Outlook - Office Support (microsoft.com).

Hope it helps! Thank you.

Stay safe & Sincerely,

Qian