So I fell in love with this idea, written beautifully in fanfic form by xxlovendreamsxx. Everyone go read it because it is completely genius. But yeah, her idea was while Sasuke is away, he sends Sakura letters via his little hawk summons! 

After all the shit my favorite characters went through, I’m a little sad we didn’t get to see much of Sakura being so open and happy with her love. It was to be expected given the circumstances, but you could tell in 699 that Sasuke just completely lit her up inside. So I wanted to show her being just a girl in love and happy with the messages Sasuke sends her.