A Send Classification in Salesforce Marketing Cloud (SFMC) is configured to handlevarious sending parameters, including the ability to send transactional emails. Transactional emails must be sent regardless of the subscriber's status, including if they have unsubscribed. This is crucial for communications such as recall notices, wherethe information is considered essential. Send Classifications have a setting specifically for transactional emails which ensures that these emails bypass the standard unsubscribe list.