Sales Insight Plug in Clarification

Hello: 

I could use some clarification.  When you are in a contact record in SalesForce, looking at the Marketo Sales Insight area, the tab for emails, is that for emails sent out of marketo from say the marketing department or does that track ALL emails even those sent out of the outlook add in.  I just want to be sure that I am explaining it correctly to our sales team.  

Any clarification would be appreciated.

Thanks!