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Unable to open .rpmsg files with Microsoft Purview Information Protection viewer

Takahiro Onodera 0 Reputation points
2025-08-29T00:48:48.08+00:00

Hello everyone,

I'm facing an issue trying to read an encrypted message and would appreciate your guidance.

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Summary of the Issue:

I received an encrypted message (.rpmsg file) in Gmail. I am unable to open it either through the web-based "Read the message" button or by using the Microsoft Purview Information Protection desktop viewer.

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Background & Steps Taken:

  1. I received an email in my Gmail account protected by Microsoft Purview Message Encryption.
  2. I clicked the "Read the message" button within the email.
  3. I successfully authenticated using my Google account and a one-time passcode.
  4. However, the web page displayed an error: "Sorry, we can't display your message right now."
  5. As an alternative, I downloaded the message.rpmsg file and tried to open it using the Microsoft Purview Information Protection viewer on my desktop, as suggested by Microsoft Support documentation.
  6. This also failed with the following error message: "Error: Microsoft Purview Information Protection does not support labeling for the current file format. The file may be in a previous Office format."

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Additional Information:

I found the following troubleshooting article, but I was unable to implement the suggested solutions due to security and permission restrictions on my company-issued PC.

https://learn.microsoft.com/en-us/troubleshoot/microsoft-365/office-message-encryption/cannot-display-message

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My Questions:

  1. Is the Microsoft Purview Information Protection viewer not capable of opening .rpmsg files? The error message seems to suggest a format incompatibility.
  2. Are there any other methods I can use to read the contents of this .rpmsg file, especially considering the restrictions on my corporate PC?

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Any help or insight you can provide would be greatly appreciated.

Thank you.

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*This was written with the assistance of AI.

Microsoft Security | Microsoft Purview

2 answers

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  1. 30225997 230 Reputation points
    2025-09-02T06:23:00.5933333+00:00
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  2. Anonymous
    2025-08-29T12:12:08.1166667+00:00

    Hi @Takahiro Onodera

    Thanks for reaching out Microsoft Q&A

    The Purview desktop viewer can’t open .rpmsg files.

    Your Specific Questions Answered

    1. Is the Microsoft Purview Information Protection viewer capable of opening .rpmsg files?
    • No: The desktop viewer cannot open .rpmsg messages.
    1. Are there other methods to read .rpmsg content?
    • Yes: Outlook (desktop, web, mobile), or retrying the Gmail web viewer in a clean session. Users could also use the MIP SDK inspection APIs, but that’s heavy setup and rarely needed for end-users.

    Please Try Below options

    1. Browser-based access
      • Retry the “Read the message” link in Incognito/Private Mode.
      • Switch browsers (Edge/Chrome tend to work best).
      • Clear cookies/session data before retrying.
    2. Use supported apps
      • Open the email in Outlook for the web (outlook.office.com) or the Outlook mobile app (iOS/Android).
      • If you forward the encrypted message to an Outlook.com or Microsoft 365 mailbox you own, it usually opens fine there.
    3. Check access restrictions
      • Confirm with your IT team whether Conditional Access or MFA policies are blocking decryption.
      • If the sender applied a sensitivity label restricting external access, only they can adjust permissions.
    4. Workarounds for corporate PCs
      • Try opening the message from a personal device/network if allowed.
      • Request the sender to resend using an alternative secure format (e.g., password-protected PDF or Purview “Secure PDF” option).
      • If possible, ask to be added as a guest user in their tenant for smoother access.

    If you have any further questions, feel free to respond in this same thread.

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