In Office 2016 for Mac applications such as Outlook, Word, Excel and PowerPoint, version 15.25, you may experience issues with IRM. This issue only occurs with on-premises RMS servers. If you are using RMS hosted on Office 365 servers and are experiencing an issue with IRM, this is not the same issue, so please contact Microsoft support.
This issue is being investigated by Microsoft and a fix is targeted to be included in the September release. Please note that the targeted release date may change due to unexpected circumstances, so please check back to this blog post for the latest updates.
Read on for more information about this issue and the resolution.
In Office 2016 for Mac applications, when you try to open an IRM protected email or document, you may be prompted for credentials repeatedly that are never successful, or you may receive the following error message: You do not have permission to open this message.
If you try to protect a new email in Outlook or protect a document in another application, the Permissions button may be unavailable (grayed out), or you receive an error message when you click it.
This issue has been fixed in the 15.26 update for Office 2016 for Mac applications. Download the update packages here:
IRM, DRM, RMS, ERM, Protected, Permissions, Restrict Permissions