How to open a .rpmsg file
Rights-protected message · Email
An .rpmsg file is an encrypted email protected by Microsoft rights management. Only the account it was addressed to can open it, and only through Outlook or the Microsoft encryption portal. There is no viewer and no workaround.
What a .rpmsg file actually is
When a sender applies Microsoft Purview Information Protection to an email, the body and attachments are encrypted and delivered as an rpmsg attachment. The permissions travel with the file.
Access is checked against the recipient identity every time, so the protection follows the message even after it is forwarded or saved to disk.
Why it will not open
Either you are not signed in as the addressed recipient, or your mail client does not support rights management. The file is not corrupt and no software you install locally will decrypt it, because the key is not in the file.
Step by step
Windows
- 01Open the message in Outlook while signed in with the exact account it was sent to. Not an alias, not a forwarded copy in a different mailbox.
- 02In webmail, look for a link in the message body that opens the Microsoft encryption portal, and authenticate there.
- 03If Outlook says you do not have permission, that is the answer: your account is not on the recipient list. Ask the sender to resend to the right address or remove the protection.
- 04Forwarding an rpmsg to a personal account will not work. The protection is tied to the original recipient.
macOS
- 01Outlook for Mac supports rights-managed messages when signed in with the correct work account.
- 02Apple Mail cannot open them at all.
What usually goes wrong
There is no legitimate bypass
Tools claiming to strip rights management from an rpmsg do not work, because the content is encrypted with a key held by the rights service rather than embedded in the file. The only route is authenticating as someone who was granted access.
Why there is no download list here
We index 177 programs and none of them opens .rpmsg files, so there is nothing for us to publish a verified download for. The software named in the steps above is the right answer for this format; we simply do not have its installer on record yet.
Common questions
- How do I open an rpmsg file without Outlook?
- Through the Microsoft encryption portal, using the link in the message body, signed in as the recipient the message was addressed to. There is no offline viewer, because the decryption key lives with the rights service and not in the file.
- Why does it say I do not have permission?
- The message was protected for a specific set of recipients and your account is not among them, often because it reached you via forwarding or an alias. The sender has to resend it to your actual address.