Count Measure based on all filters or columns except one

So I've got a table looking something like this that lists communications that have been sent and via what method

What I want is to put it into a table like this in a Power BI report

Now the first 4 columns are easy, but what I need is a measure for the last column. I need it as a measure as I would like it to work with filters. For example if I filtered to just PM, then the value should update.

The difficulty I'm having is that it's easy to count all rows. I can even count all rows that match just the customer ID and Message, but what I can't do is count all rows that match everything (those two columns plus any applied filters) regardless of the delivery method column.

Any help would be appreciated, thanks.

Edit: can't get the table to display correectly. It looks correct when I edit the post and if I try and change the column width I get an error saying invalid html