"A unique identity matching the From address was not found. The message will be sent using the current From field and settings from identity dennis george <poohpah@att.net>"

When I open a message in my att.net inbox, thunderbird opens it in a Write window as if I am going to send it instead of just reading it. The From field is my att.net address (poohpah@att.net), The Reply-To field is the sender of the message, and the To field is my att.net account. There is also a yellow box at the bottom of the window that says: "A unique identity matching the From address was not found. The message will be sent using the current From field and settings from identity dennis george <poohpah@att.net>" This does not happen in my gmail.com account - it opens messages normally. Version is 115.4.1 (64-bit) Example attached as: Thunderbird_issue_screen_image.png