1. Start Outlook for desktop.
2. Click on "File" in the upper left of Outlook (Image 1), and from the pane click "Manage Add-ins" (Image 2) This will launch and sign in Outlook for the web.
Image 1
Image 2
3. Close the pop up "Add-Ins for Outlook."
4. Click on any email to open it in the viewing pane.
5. In the upper right corner of the email, click on the ellipsis (three dots). A menu will open, click on OneNote.
6. You should see the authentication process for OneNote, and then a list of your notebooks. Click "Cancel."
7. Close the browser window with Outlook for the web.
8. Open Outlook for desktop, and click the "OneNote" button
8. It should authenticate and allow you to Send to OneNote now.
9. Select the OneNote folder to send the email to, and click "OK."