Validating your email list in HubSpot is a necessary step to improve and maintain email deliverability. By utilizing Clearout's HubSpot Email validation integration, you can ensure that your email list is free of bad, disposable, and fake email addresses before sending any emails. This integration allows you to securely import and export data between HubSpot and Clearout, making the validation process seamless and efficient. With a clean email list, you can increase the chances of your emails reaching your intended recipients and avoid being flagged as spam or blocked by email providers.