We know that in Harry Potter and the Sorcerer's Stone, Hogwarts was able to locate Harry at all of his different addresses in order to deliver him his letter. So, my question is, couldn't they have done the same with Voldemort to find him? Is it possible that Voldemort put protective spells around him that stop him from being located?
We also know that in Harry Potter and the Deathly Hallows, Hermione puts some protective spells around their campsites. However, none of them (after a bit of research) actually prevent someone from locating them. Couldn't Voldemort, in turn, have done this?