For all unique in Column A, return number of unique in another column

Here's a sample of my data:

Capture.PNG

I need to know the following: "For all unique values in Column A, return the number of unique values in Column E.

In other words, I need to know how many unique interactions took place (as determined by a unique date) for each ID.

I am probably a low-to-mid range Excel user, but I have no idea where to start.

Thanks in advance.

Try this ...

=SUM(IF(A2:A20<>"",1/COUNTIFS(A2:A20,A2:A20,E2:E20,E2:E20),""))

Array formula, enter with Ctrl+Shift+Enter.

This worked perfectly. Thank you for the quick response!