In this blog series, the importance of maintaining good deliverability for email is emphasized, particularly for transactional emails which are critical to business operations. The author argues that manual account approval helps ensure reliable delivery by separating transactional and bulk emails, as engagement rates differ significantly between these types of emails. Transactional emails like password resets and receipts see higher open, read, and click rates than bulk promotional emails, making them more valuable to customers and requiring better delivery reputation protection. To achieve this, senders need to use separate domains, IP addresses, and email addresses for each type of email, and utilize tools that track and troubleshoot missing emails, as well as closely integrate with systems for seamless bounce handling and tracking. Ultimately, separating and protecting one's reputation is crucial for maintaining good deliverability, particularly for critical transactional emails.