Now that's what I call email marketing

Subject: Google Agency Party - Your Invitation

Dear [Fname]

We would love you to join us for a Party on the night of Thursday September 28th. We sent you an invitation this afternoon, but due to some technical difficulties on our side, the invitations were not sent in the correct format.

We will be resending your invitation shortly. Please look out for it and we do hope you will be able to join us.

All the best,
Valentina

Of course it being an advertising thing I'm sure most recipients replied as "fname".