Hamlet's Letter to Mom

Enter a Messenger

How now! what news?

Messenger

Letters, my lord, from Hamlet:
This to your majesty; this to the queen.

KING CLAUDIUS

From Hamlet! who brought them?

Messenger

Sailors, my lord, they say; I saw them not:
They were given me by Claudio; he received them
Of him that brought them.


KING CLAUDIUS

Laertes, you shall hear them. Leave us.

Exit Messenger

Reads

So I was reading Hamlet Act 4 today and noticed something. The messenger brings letters, clearly stated one for the king and one for Gertrude. Claudius then reads about Hamlet's return, he discusses the plan with Laertes, and then Gertrude arrrives to tell of Ophelia's death.

Does Gertrude ever get her letter? What's in it, do you think? Is any mention made of it again?