What should also work, but I haven’t tested, is:
dbus-send --session --dest=com.nokia.profiled --type=method_call /com/nokia/profiled com.nokia.profiled.set_value string:"ambience" string:"email.alert.enabled" string:"Off"
Look up values with:
dbus-send --session --dest=com.nokia.profiled --type=method_call --print-reply /com/nokia/profiled com.nokia.profiled.get_values string:"ambience"