Prior to V115 (Supernova), using the two extension buttons Send Later (in compose mail) and Get/Send (in the compose mail toolbar) worked well in tandem to easily facilitate composed emails being sent later with simple clicks. The former to place composed emails in the Outbox and the later to send emails from the Outbox. Unfortunately, the Get/Send extension is no longer supported in V115. Send Later is still there and working. Thunderbird provides send unsent messages via the File menu or a right click on the Outbox. It would be much smoother and consistent for there to be a Send Unsent button on the main mail toolbar. Please take this as a request to provide the above at the earliest opportunity. Thanks.