The best trick of this trade I've ever used is this:
Call the journalist/paper and ask if they received your package yet (before you send it). Describe the package as it would have been sent... colours, what was in it, the name of the band, etc. If the journalist gets a lot of packages that he never opens, it will be obvious in the way he looks for the disc. The journalist will either give you a hint that he doesn't open the packages that often, or he'll ask about the music that you're playing. Have a good description of what you're doing ready so you don't blow this pitch. When he "can't find" the package, offer to send another one out by express mail so he can check it out. Seem puzzled that the first package didn't get there or you'll be caught.
This weeds out all the people who aren't going to listen to the disc anyway and gives you an "in" with the people who would. Then, you're not sending the package cold anymore... he'll be expecting it and might even call you to let you know that he received it.
It's sneaky, but it works.