I'm glad to hear from you.

很高兴收到你的来信。

Dear Chris, I am so glad to hear from you.

亲爱的克里斯，我很高兴收到你的来信。

I am so glad to hear from you too, gran. Miss you so much.

我也很高兴收到你的来信，奶奶。非常想念你。