Currently the HubSpot connector only supports the email_campaigns and email_events tables in the schema. This is problematic for certain mailing types, as statistics can be spread across multiple sends (including for A/B split mailings which will have different IDs for each segment and have no parent ID to marry them, and the same with RSS campaigns).

The proper way to handle these in the HubSpot paradigm is to use the Marketing Email API endpoints, which can contain both information about the send (e.g. type, publish date, list details, settings, sender details, etc.) as well as statistics (open/click/send/bounce) aggregated at the campaign level. It also contains the key tying child campaign IDs to the appropriate marketing email, as well as the only way to get the preview key needed to build links to preview a mailing.

This type of campaign data is essential for anyone integrating clients who use HubSpot as their marketing ESP and not just as a CRM.

The endpoint that should be added is documented here (this version includes the aggregate statistics):
https://legacydocs.hubspot.com/docs/methods/cms_email/get-all-marketing-email-statistics

Most of this could be represented as a flat table, but there are several array type values such as the list of campaign IDs that would need to be preserved.

Not only would this endpoint allow for reporting on all campaign types, it would also provide the ability to visualize all campaign statistics as well as see upcoming or draft campaigns and integrate them with other systems.