Gradebook

Hi all,
I would like to import a csv file that contains student emails and their final Letter Grade into the gradebook. No gradebook calculation is needed.
It seems simple enough but I never figured out a way to do it. I was only able to create a Scale grade item and map the final grade on the csv file to it, but how do I change the calculation setting of the Course Total so that the final letter grade can be displayed to students?

Thank you all for your help.