To automate the labeling of sent emails in Gmail, one can use the BCC feature along with Gmail’s filters and the AutoBCC extension from cloudHQ. The process involves setting up AutoBCC to automatically BCC oneself on outgoing emails based on specified rules, such as the recipient’s email address or subject line. Afterward, Gmail filters can be configured to apply labels to these BCC’d emails, allowing for automatic organization of sent messages. This combination offers an efficient way to keep a well-organized inbox by ensuring that all sent communications are automatically categorized and easily accessible.