There's a new version of the HubSpot API

Starting November 30, 2022, API keys will be sunset as an authentication method. Learn more about this change and how to migrate an API key integration to use a private app instead.

How Does HubSpot validate email addresses?

HubSpot will validate the email address used for any process that would create or update a contact record.  This includes using the Contacts API to create or update a contact directly, and also the processing of any form submissions or events. Learn more about how HubSpot validates email addresses.