Senior Member

Currently we have a session policy in Microsoft Cloud App Security that blocks all file downloads while using Outlook Web which still allows attachment viewing. This works great for all Office documents however .PDF attachments cannot be viewed because they perform a download when previewing them. The only workaround is allow .PDF attachment downloads only. Will there be any future enhancements in MCAS that will allow .PDF viewing while still blocking downloads? 


Previewing or printing PDF files may be blocked

This is normal behavior when you have a policy configured to block downloads. Occasionally when previewing or printing PDF files, apps initiate a download of the file causing Cloud App Security to intervene to ensure the download is blocked and that data is not leaked from your environment.

If you would like to allow PDF file downloads, you can exclude PDF files based on their file extension in the relevant session policy.

Well, I understand, that PDF needs to be downloaded to read it, at least so far. Anyway, it looks like there was an option to read PDFs in Office Online? (
Since PDF is a very common file format, it would be great to be able, to read them online - without the hassle of downloading these files and the disadvantage of the possibility to forget to delete such a file on a "public accessible" device.
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