How to restore the People Pane in Outlook 365

Microsoft has retired the People Pane, but you can still get it back ... albeit not in the Outlook desktop app itself.

1. Log in to the corresponding Outlook web app. You can find this via File -> Info -> Account Information -> Account Settings -> below Access this account on the web. If you do not have a corresponding Outlook web app, this method will not work
2. In the Outlook web app, find the message you want to see people details for
3. Mouseover the name of the person of interest in the email header
4. To the right of the Call icon, mouseover the V icon

The ensuing dropdown menu provides much of the People Pane's functionality, including finding previous emails, attachments, and more.