I'm not getting notifications anymore, when a new email in Thunderbird arrives.
How can I fix this and continue getting notifications? I'm running Ubuntu 12.04 with the Xfce desktop environment.
I had the same issue in 12.04 and now in 12.10. I thought the notification of email arrival was not working. In actuality the alert was working, only it was inaudible. From a terminal session I ran 'sudo pavucontrol'. I selected the 'Playback Tab' then adjusted the 'System Sounds' slider to midway between 'Silence' and '100%(0db)'. This solved the issue for Thunderbird and other other applications such as Free Cell.
I am not a Linux sound expert. I believe the settings for 'Output Volume' sound in the 'Systems Setting' on the Output Tab should have worked worked but they did not. The 'pavucontrol' program did work though. The email alerts stopped after an update to Ubuntu 12.04 and 12.10. I believe during the update the volume control was reset and that is why it appeared the alerts and other sounds appeared not to work.