Hi Adam,
Thank you for this feedback. The ability to unbounce a contact from the contact’s timeline is a feature that is only available within Matketing Professional and Marketing Enterprise accounts. Within a Marketing Starter subscriotion, you’ll need to open a support ticket to request that contacts be made eligable for marketing emails again, and provide evidence that the contacts are deliverable.
You can also review why contacts have hard bounced within the post send screen of the marketing email tool for the campaign that caused the bounce. Reviewing the bounce reason can help to understand why the mail was rejected by the recipient’s mail server, which will help you to understand what may need to be adjusted to prevent more of the same bounce types in the future. You can read more about the different types of bounces here.