Quote from datarecovee on August 25, 2026, 9:36 am

The RPMSG file extension refers to a protected email message in Microsoft Outlook and Microsoft 365. The abbreviation RPMSG means Restricted Permission Message and is often used when the message has been encrypted or protected via the use of information rights management or message encryption by Microsoft. In contrast to typical file extensions like PDF or DOCX, an RPMSG file is not meant to be opened with a regular application by default. The protection of the message will require an additional application like Outlook, Microsoft's protected services, or authentication by means of the authorized account. In case you get the RPMSG attachment, it is better to open the message itself rather than the attached file. Whether you will be able to open the message contents or not will depend on the permissions set by the sender.