Comment 2 for bug 878941

I figured out the problem. In mail-notification the mail-notification applet only sends notifications if ubuntu is running a "stracciatella gnome" session. Stracciatella-gnome-session was a "vanilla" gnome session with very little ubuntu. Presumably mail-notification turns itself off for the regular ubuntu gnome session because of the evolution indicator.

However! Now that ubuntu has moved to unity, the gnome-shell session doesn't have the evolution-indicator conflict anymore and mail-notification should be enabled.

The way to fix this would be to remove the is_stracciatella portions of the mail-notification plugin.