Order Rank on Sales Data

Hi,

I'm struggling to add a new column to my dataset using a dax calculated column. I want it to look something similar to this:

Columns A-D are in my dataset, and I want it to have a running count so that every time a distinct email plays for an order, their count will go up by 1. This way, I'll be able to see how many times a product is the first bought item (ie to find out if Apples is the most purchased first item, then bananas etc).

Any help would be super appreciated!