FedEx Express handles more than 6.5 million packages everyday in nearly 220 countries and regions. Customers expect timely and accurate information on their package deliveries. To address customers demand, I have worked with teams across different departments (e.g., IT, market) and colleagues in the Operations Research and Spatial Analytics (ORSA) to develop and deploy a machine learning-based solution to produce customized expected delivery time windows for millions of packages every day. I am proud that the deployed ML model has been in production with reliable performance since March, 2021.