SharePoint Online: How to Configure Information Rights Management (IRM) to Protect Documents?

Requirement: Configure IRM in SharePoint Online.

How to enable information rights management in SharePoint Online?
Information Rights Management (IRM) Polices in SharePoint Online protect sensitive content from unauthorized users by preventing users from printing or saving copies of a file. Information Rights Management can be applied on Office documents such as Word, Excel, PowerPoint and PDF, XPS files.

Step 1: Make sure Rights Management is Activated in the Microsoft 365 Admin Center

Unlike SharePoint On-premises, you don't have to install anything to implement IRM as Office 365 comes with pre-installed. IRM settings are scoped at the list or library level. However, You must activate the Information Rights Management Service for the organization from the Office 365 admin center first before IRM can be applied to the SharePoint library or list. To activate IRM in Office 365, follow these steps:

• Login to Microsoft Admin Center at https://admin.microsoft.com
• Expand Settings from left navigation >> Click on Settings >> Click on ‎"Microsoft‎ ‎Azure Information Protection"
  
• Click on "Manage ‎Microsoft‎ ‎Azure Information Protection‎ settings >> Make sure Rights management is activated.
  

Office 365 provides IRM service through Azure Active Directory Rights Management which is included in E3 and E4 plans.

Step 2: Enable IRM in the SharePoint Online Admin Center

Once IRM is enabled at the Office 365 admin center, the next step is to activate IRM in SharePoint Online.

• Login to SharePoint Admin Center >> Click on Settings >> Click on "Classic settings page" link.
• Scroll down and find "Information Rights Management (IRM)", Set " Use the IRM service specified in your configuration "  and then click on the "Refresh IRM Settings" button.
  
• Click on the "OK" button on the bottom to commit your changes.

This will enable IRM service to document libraries in the tenant. Wait for some time, It took 30 min for me!

Step 3: Activate IRM on SharePoint Online List or Library

Once IRM settings are enabled at the tenant level, site owners can protect their documents with IRM. To apply IRM encryption a document library, do the following:

• Go to the list or library settings >> Click on the "Information Rights Management" link under the Permissions and Management section. If you don't see this link - Information Rights Management (IRM) service may not have enabled either in your Office 365 or in the SharePoint Online Tenant settings.
  
• On the Information Rights Management Settings page, select the "Restrict permission" to documents in this library on the download checkbox for applying permission to documents. Enter a  name for the policy in In the Create a permission policy title input box and provide a description in Add a permission policy description input box.
  

You can click on "Show Options" to expand IRM Library settings and select the restrictions that have to be applied for documents in the library and click OK button.

Once the IRM is enabled for a list or library, any supported file in that library can be protected. Similarly, When you enable IRM for a list, rights management applies only to files that are attached to list items (But not to the list items!) IRM needs to be configured in every list and library that you want to protect.

Please note, IRM protected documents cannot be edited in the browser. Also they do not support co-authoring!

Every document that you upload to SharePoint gets encrypted and when you try to open any of those encrypted documents it authorizes your credentials with office 365 security servers. So you can specify what each user should be able to do with this document to protects against any accidental leakage of your information. You'll see "Restricted Access" message when people download files in an IRM-enabled list or library.