This document provides guidance on conquering the Gmail inbox by focusing on the user experience. It discusses that Gmail prioritizes inboxing emails that users want, so content and permissions must align with user intent from the start. Engagement over the user lifecycle is key, as positive interactions like opens and clicks help the sender's domain reputation, while lack of engagement or complaints can lead to spam filtering. Technical best practices like SPF, DKIM and DMARC authentication, warming up new IPs and domains, and optimizing for mobile are also covered.