These three letters are filled to the brim with joy and hope and promise. Celie tells God that she finally holds a letter from Nettie. Nettie's letter with the funny-looking stamps is proof that not only is Nettie alive, but that Celie's babies — Olivia and Adam — are also alive and are "coming home before the end of another year." Celie's joy, you should note, is doubled because she has someone to share it with: Shug.
We realize that Nettie, although she is now a missionary, is not and never was as naive as Celie was. She is aware that Albert has probably been hiding her letters from Celie, but she counts on the sentiment associated with Christmas and Easter to perhaps soften his fierce resolve to punish both her and Celie by keeping her letters from Celie.
How do we know that Albert has been deliberately cruel and vindictive for all these years? From two things that Celie says, and Celie doesn't lie. Initially, she tells Shug that Albert couldn't have kept Nettie's letters from her because he knew that Nettie "mean everything in the world to me." But later, she tells God that she finds the letters in Albert's trunk, and everything that mean something to Albert go in his trunk. Clearly, Albert has structured his life around deliberately punishing both Nettie and Celie — for Nettie's rebuff long ago and for Celie's not being either Nettie or Shug.
