open a terminal (CTRL+ALT+T) and type sudo apt-get update && sudo apt-get install -y evolution-plugins.
this should do the trick for the notifications while evolution is open... maybe you have to configure/activate/deactivate some of these plugins in Evolution via Edit, Plugins.
if you want a notification without evolution running in the background, open a terminal (CTRL+ALT+T) and type sudo apt-get update && sudo apt-get install -y mail-notification-evolution.
this will install a little extra program checking for mails in the background without having the mail-client running. maybe you just have to configure it to your needs via the launcher in the control center.