Every link in an email sent from HubSpot contains identity tracking parameters so visits from links clicked in emails are attributed to the correct contacts.
These parameters, _hsenc and _hsmi, are unique to HubSpot and are not recognized by Google Analytics. In your Google Analytics report, you may see that each URL clicked from an email is considered a unique, separate page due to these unrecognized tracking parameters.
You can filter these query strings out of your report so that all visits to landing pages that contain those tracking parameters are bucketed together:
Please note: values must be comma-separated when entered in the Exclude URL Query Parameters section, not entered as separate line items.
Please note: after applying these filters, your data won't be filtered retroactively.