If you get the box, who you should send it to?
A proposed recipient should be someone you suspect of having a critical mass of (or at least sufficiently interesting) electronics junk, should have a non-zero online presence, and should be reliable enough that you think they actually will send it off again within two weeks. (Naturally, bonus points for open source oriented hardware hackers.)
Why would you want to get a box of junk in the mail?
As Mark Frauenfelder observed in Make: vol. 12, there is a certain importance to keeping a junk box for future projects. We heartily agree. Perhaps a component in the box-- or the box itself-- will inspire your next project. Or just maybe it will have that frobnicated interoceter you've been looking for forever. Or maybe you just want to join our fledgling junk-sharing movement because it's fun.
Don't sweat the details.
Can you say "no" if someone offers you the box? Yes. Can you send it to the person whose name you wrote down? Yes. Can you send it to someone who already has a checkmark by their name? Yes. If the box gets too full, can you split the contents in two and send them in two different directions? Yes (but don't forget to add a new book to the new box).