A system design where email services and resources are spread across multiple servers or data centers rather than being concentrated in a single location. This approach enhances reliability, scalability, and performance by distributing the workload and reducing the risk of a single point of failure. Distributed systems can improve deliverability and resilience by ensuring that email sending, receiving, and storage functions are managed across various geographic regions or servers. This distribution helps handle high volumes of email traffic, balances the load during peak times, and provides redundancy to maintain service continuity in case of hardware failures or other issues. Overall, distributed infrastructure supports more robust and efficient email operations, contributing to better service reliability and user experience.