Why does one invalid email cause an integration to fail in HubSpot?

Hi @RMazzucchelli7,
As per my recommendation, you should skip the email property data in case of an email validation error. HubSpot also allows creating a record without an email. If you still want to store the invalid email, you can use a separate input field to capture it. For this, please use the basic (single-record) API instead of the batch API, as it will be easier to handle email validation logic.