To clarify, are you using this endpoint and trying to determine which
OPEN, etc. events are associated with certain HubSpot marketing emails?
If so, you can use the
emailCampaignId value for each event. Every
campaignId reflects a specific send of a marketing email. You can cross-reference the IDs with the values from the Get all campaign IDs and Get campaign data for a given campaign endpoints.
Engagements with the type
EMAIL, on the other hand, are not marketing emails. Opens and clicks for these emails cannot be retrieved with an API. This topic goes into a bit more detail.