I have a E71 and the notification light is always on breathing light. I have no emails, sms, mms, misscalls or voice messages. I even turn off the notification light off for everything and is still breathing. It is kind of annoying not to know why is breathing.

It’s the “Breathing light” that you need to turn off, rather than any notification:

Tools –> Profiles –> General (or whichever profile you use) –> Personalise –> Breathing light –> Off

Try this and see if it helps.