Apple Mail

My laptop is a Macbook Pro (early 2015) with system OS 11.0.1 (Big Sur). Apple Mail used to put mail that didn't go through in the Outbox, and/or would let you know that the message didn't go through. These features seem to have disappeared. Two messages were not sent and I didn't get any feedback on them; they also disappeared from the application, not showing in the Draft folder, and there is no Outbox folder any more, where failed messages used to be stored. As a result I have to check in the Sent folder whether or not each message I sent went through, and I need to recompose those that didn't.