After some research I found a 4000 year old love letter that was written in Cuniform on a clay brick in Babylonia.
To Bibeya, from Gimil-Marduk. May Shamash and Marduk grant you, for my sake, to live for ever. I write this in order to enquire after your health. Let me know how it goes with you. I am now settled in Babylon but I am in great anxiety because I have not seen you. Tell me when you will come, that I may rejoice. Come in the month of Arakhsamna (November). May you, for my sake, live for ever.
Not much of a love letter by today's standards but they lived in a different world than we do. I wonder if Gimil-Marduk created the clay brick himself or if he had to pay someone to do it for him.