Unable to Open IRM protected Excel Files Emailed to Our Organization

Question

Sometimes when another organization emails us, we are unable to open the file attachment. The file is an Excel file. When opened in Outlook web mail, we get the following error:

Couldn't Load This Workbook
We're sorry. We can't open the workbook in the browser because it uses these unsupported features - Workbook protection.

When we open the file in Excel Desktop, the user is prompted with a notice, configuring your computer for information rights management. Then, the user is prompted to sign into Office again. The user does so and then an error message pops up with the sender's company logo stating that the selected user account does not exist in tenant.

I don't understand why it would be asking the user to sign into the sender's Office tenant. We're using Office 365 MSO 64-bit and fully updated.

We use Mimecast to send secure emails. Do we need to set up something in Office 365 in order to open other Office 365 tenant's protected files?

Thank you.

Answer 1

Hi @Anon4343

I'm primarily responsible for general issues of Office clients on Q&A forum ~

Your issue is more related to Azure Information Protection and Office Administration (Microsoft 365 Admin Center).

The following document is I personally found on the web and hopes it is helpful.

Credentials don't work for IRM-protected content

In my opinion, if you need to access the IRM protected files, you need to authenticate to sender's Office tenant to obtain the key. It is by design for file security.
If this organization has set up some conditions, such as Conditional Access, authentication may also fail.
It seems that if the sender's administrator invite you, and you redeem the invitation to let your account provisioned in their resource tenant, then you can access the file.

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