The Postmark team migrated their software application from a colocated data center to Amazon Web Services (AWS) over the course of two years. The team aimed to improve the reliability, operability, and scalability of their system while ensuring minimal disruption to customers. To achieve this, they adopted various tools and techniques, including Infrastructure as Code (IaC), Prometheus for monitoring, Grafana for visualization, Ansible for automation, and Terraform for provisioning resources in the cloud. The team also implemented region-awareness in their services, allowing them to route traffic between different data centers. They gradually shifted customer traffic from the colocated data center to the new AWS infrastructure, ensuring a smooth transition. While not all goals were achieved, the migration has led to improved reliability, availability, and performance for Postmark's customers. The team's approach was incremental, slow, but ultimately successful in reducing stress for the team and delivering a reliable product to customers.