Well, not if you make a mistake that leads to you being unable to send a message back. That's part of the plot of a sci-fi story I read: there's a machine tha

Well, not if you make a mistake that leads to you being unable to send a message back. That's part of the plot of a sci-fi story I read: there's a machine that does this, and the messages stop at a specific point in the future. (It's 'the Arrows of time' by Greg Egan. The Orthogonal trilogy is good stuff.)