User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:84.0) Gecko/20100101 Firefox/84.0
Steps to reproduce:
Received an e-mail message in Thunderbird. Added the sender’s display name and e-mail address to my address book contacts. Made sure that the Display name option to Show only display name for people in my address book under Tools >> Options >> General is checked.
The Message List Pane is still showing the From: message header rather than the display name in the address book.
The Message List Pane should show the display name of the sender.