It's way, way worse.

You can't put wet clay directly in an oven, it will crack. So it has to dry first. But if it's dry, it's hard enough to withstand travel, as long as you put it in an envelope of clay (different quality, I assume, as the receiver will have to be able to break it away without damaging the letter). Basically they didn't go through the trouble of cooking them for something ephemeral such as letter.

Inside Ea-Nasir's oven and strewn around his house, they found several cooked complaint tablets. This led some to believe that Ea-Nasir collected and rejoiced in re-reading the complaints. Or maybe a disgruntled employee wanted to send hard proof to the BBB.

Gotta make sure that tablet really roasts