More on storage

I am going to be needing a new storage box.... This one is bursting at the seams (does a box have seams?)

with plastic zip wallets filled with letters. I think one correspondence has lasted more than 4 years, perhaps I could archive some of the early letters into a new zip folder to store elsewhere (perhaps I could scan them in as well). I'll also need to sort through my "failed" correspondence box, perhaps scan these in and bundle up to store less handily.