Why is the Pin icon not available in the FYI Drawer in Outlook?

Pinnable task panes are currently available to Office 365 subscribers using Outlook 2016 or later on Windows (build 7668.2000 or later for users in the Current or Office Insider Channels, build 7900.xxxx or later for users in Deferred channels), Outlook 2016 or later for Mac (version 16.13.503 or later), and Outlook Online. Refer to this Microsoft article.

In Outlook, to keep the FYI Drawer always open, click the Pin icon. This will save it from reloading each time.

If you do not see the Pin icon in the FYI Drawer in Outlook, you may need to update the version of your Office 365.

 To check Outlook version:

1. Open Outlook.
2. Click File >Office Account.
3. In the About Outlook you will see the version and build of Outlook that you are using.