This connector integrates with the Marketing Email API and gives you stats and metadata on outbound marketing emails sent from within HubSpot.
The stats you can get out:
sent
open
delivered
bounce
unsubscribed
click
dropped
selected
spamreport
suppressed
hardbounced
softbounced
pending
contactslost
notsent
Some of these also have ratio metrics that compares with the grand total.
There are more information in HubSpots API documentation. Read more about email metadata fields here. And details about the stats you can get out can be found here.