Open Any RPMSG File
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An .rpmsg file (Restricted Permission Message) is an encrypted email format created by Microsoft Outlook using Information Rights Management (IRM) or Azure Information Protection (AIP). It protects sensitive email content by encrypting it and restricting what recipients can do — preventing forwarding, copying, or printing. If your email client doesn't support IRM natively, it receives the protected message as a message.rpmsg attachment instead of displaying it inline. Read our full RPMSG guide →

Yes! You have several options without the desktop Outlook app: (1) Outlook Web App at outlook.com — log in with the account that received the email; (2) Microsoft OME Viewer — click "Read the message" in Gmail or other clients; (3) Outlook Mobile App on iPhone or Android. Our viewer helps you understand the file and directs you to the right method. See all 5 methods →

You received a message.rpmsg attachment because the sender used Microsoft's Information Rights Management to protect the email — common in corporate environments for sensitive communications. Your email client (Gmail, Apple Mail, etc.) couldn't display IRM-protected content natively, so it showed it as an attachment instead. This is normal and legitimate behavior in enterprise settings — though it has also been exploited in phishing attacks (see our RPMSG phishing guide).

Yes — because your file never leaves your browser. Unlike other "online viewers" that upload your file to a server, our tool uses a pure JavaScript parser that runs entirely in your browser. We have no server that could store, log, or process your file. RPMSG files often contain sensitive business information — that's exactly why we built the tool this way. You can verify this by opening your browser's DevTools → Network tab and confirming no upload requests are made.

The email body inside an RPMSG file is encrypted with Microsoft's Rights Management Services. This encryption is cryptographically tied to your specific Microsoft account identity. To decrypt it, a system must authenticate with Microsoft's RMS servers and verify you are an authorized recipient. No third-party tool — including ours — can bypass this without your Microsoft credentials. Any tool claiming to "decrypt" RPMSG content without Microsoft auth is either lying or creating a significant security risk. We're honest about this.

If you received an RPMSG-protected email in Gmail: (1) Open the email in Gmail; (2) Look for a "Read the message" button or link in the email body; (3) Clicking it opens Microsoft's OME (Office Message Encryption) viewer in a new tab; (4) You'll need to authenticate with a one-time passcode sent to your email, or sign in with your Microsoft/Google account. Gmail itself cannot open the .rpmsg attachment — you must go through Microsoft's viewer. Full guide for Gmail, Android & iPhone →

RPMSG phishing is a growing attack technique where hackers send malicious .rpmsg files through compromised Microsoft 365 accounts. Because the content is encrypted, traditional email security scanners can't inspect it. The victim is tricked into "authenticating" to view a "protected message" — actually handing credentials to the attacker. Red flags: unexpected RPMSG from unknown senders, urgency about viewing a "confidential" message, login pages that look slightly off. Always verify unexpected RPMSG emails with the sender via phone or separate chat before clicking anything. Full RPMSG phishing guide →

RPMSG: Encrypted, rights-protected Outlook message (IRM/AIP). Requires Microsoft authentication to open. MSG: Standard Outlook message format (OLE/MAPI). Contains full email with all headers and attachments but is NOT encrypted. Can be opened with Outlook or MSG viewer tools. EML: Standard MIME email format used by most email clients (Gmail, Apple Mail, Thunderbird). Plain text, widely compatible, not encrypted. Full comparison guide →