.RPMSG File Extension

An RPMSG file is a protected email message created by Microsoft Outlook, Microsoft's email and calendar application. It contains an email that has been encrypted such that only certain users can view, print, copy, or forward it. RPMSG files are sent as attachments to standard email messages; these attachments use the filename message.rpmsg.

Outlook users can use the program's information rights management (IRM) features to protect emails they send. When a user protects an email this way, Outlook compresses and encrypts the message's contents, as well as any permissions the sender has specified (e.g. restrictions on forwarding or printing the message). It then saves this encrypted version of the message as an RPMSG file.

The RPMSG file is sent to recipients as an attachment to a normal Outlook message. The message explains it contains protected content, and it includes a link that can be used to open the RPMSG file. Only specified recipients can open RPMSG files.

NOTE: Azure Information Protection also creates encrypted email messages saved as RPMSG files.

In Microsoft Outlook and other email applications, you can open a protected email message by clicking the message.rpmsg file attached to an email. When using an application other than Outlook, you may be redirected to a separate webpage to view the protected message.

Keep in mind that you can open a protected message only while logged in to an email account to which the message was originally sent.