I'm using Apple Mail 16.0 (3618.104.22.168.1) on macOS Monterey 12.6.2 (21G320).
I remember there used to be a sound called “Glass” or similar. I was using this for incoming e-mails some months/years ago.
You can hear that sound here.
Unfortunately, I cannot find that sound in the list of sounds in Mail preferences any more:
Is there a way to use this sound for incoming e-mails?