Cannot Preview PDF attachments in Outlook Web Access

Barry,

I've found the cause of the problem.  It is a setting in O365 Outlook Admin Policy settings.  

If you sign on to O365 as admin and go to Exchange Admin.  Click on Permissions and then on "Outlook Web App Policies" and you should have a policy.  Highlight it and edit it by clicking on the Pencil icon.  Then click on the "File Access" link to get the image below.  If you UNCheck the "Direct File Access" box and then click on the "offline Access" link and choose NEVER radio button.  Save your changes and then wait about an hour or 2 for the policy to take effect.  You will no longer be able to preview PDF docs in Outlook Web Access.    Our admins disabled direct file access to prevent people from down loading attachments to non-company PCs.    I can now tell people that this is a security feature but that won't make them any happier.    Is there another way to allow PDF files to be previewed in OWA without allowing attachment download?   Sincerely, buckybear3819

Hi Buckybear3819,

Very thanks for your update.

Yes, you can run PowerShell commands to add pdf as the allowed file types. Please invite an Office 365 admin and perform the below steps:

1. Connect to Exchange Online PowerShell with an Office 365 admin account.
2. Run this command to check the AllowedFileTypes in your organization

Get-OwaMailboxPolicy OWAMailboxPolicy-Default | select -ExpandProperty AllowedFileTypes

3. Run this command to add PDF to the AllowedFileTypes

Set-OwaMailboxPolicy OwaMailboxPolicy-DefaultMailboxPlan -AllowedFileTypes @{Add = '.pdf' }

Note: Please replace OwaMailboxPolicy to your Outlook Web App policy’s name.

Regards,

Barry

Hi Barry,  I ran the Get-owmailboxpolicy command to display the allowed filetypes and PDF is included among the allowed filetypes, along with the doc, xlsx and pptx filetypes.   I doubt adding the PDF file type will help at this point.

Hi BuckyBear3819,

Thanks for your updates. To further investigating this problem, could you give us the screenshot of the entire PowerShell commands interface? We will deliver it to our related team and check if they can provide further assistance.

Thanks,

Barry

Hi BuckyBear3819,

Per checking the official article, we found that you will not be able to use the allow, block, focus save feature if the Direct File Access is off. So, as your organization set the Direct File Access as off, it’s an expected behavior that your users are unable to preview PDF files in Outlook Web App.

As a workaround, we recommend that you enable Direct File Access, block all the file types and only allow PDF file type in your organization. For more details, see this article: https://docs.microsoft.com/en-us/powershell/module/exchange/client-access/Set-OwaMailboxPolicy?view=exchange-ps

Regards,

Barry