In this blog series, Plushcap discusses the importance of manual account approval for maintaining good email deliverability. The author argues that while using a dedicated IP address can help improve reputation and delivery, it's not a silver bullet and has its own set of caveats, including increased costs, potential impact on sending volume, and need for warming up new IPs. In contrast, sharing a pool of well-policed shared IP addresses is considered the best bet for most senders, as long as messages are well-policed and customers don't have to request changes. Postmark takes full responsibility for deliverability, monitors abuse and misuse, and ensures that customers are on healthy IP addresses, allowing them to focus on sending instead of worrying about reputation. The author emphasizes the importance of shared responsibility in maintaining great delivery and highlights Postmark's commitment to providing a reliable email service with closely monitored senders.