@BMelville I haven’t implemented a solution for internal communications within HubSpot for this exact reason - it’s hard to separate the stats. One option you could explore would be to create an internal Business Unit, but that would change the pricing of your plan, and it would also likely require joining a new beta for how emails are handled with business units to fully separate them.
There are so many good internal communication tools out there, I typically recommend one of those as an alternative because that’s what they’re designed to do and it’s not what HubSpot email is built to support.
I hope this helps!