Things You'll Need
Instructions
Unfold the letter and remove anything attached to it, such as a paperclip, post-it note or staple. In time, these materials will damage the letter and cause discoloration or fading.
Place the letter in a polypropylene sleeve, which is available at most department, craft or collectable stores.
Place the polypropylene sleeves in a storage box or 3-ring binder. Store the letters in an area that is roughly 70 degrees Fahrenheit with 40 percent humidity. This climate will keep the letters from becoming too dry, and potentially falling apart, or developing mold.