Registered Mail Enterprise Core System integrates real-time APIs, batch processing, and file-based transfers across a DMZ-protected architecture serving external customers, digital channels, and internal postal operations. Data flows from external consumers through IBM DataPower Gateway for API security and routing, then through iConduct orchestration into an ESB layer for transformation and file processing before reaching Oracle operational and data warehouse systems. This architecture demonstrates enterprise integration patterns for high-volume transactional systems requiring strict security boundaries, multi-channel ingestion, and centralized observability. Fork this diagram on Diagrams.so to customize the ESB topology, add monitoring dashboards, or adapt it for your own multi-system postal or logistics platform. The identified bottlenecks at the Services Server (ESB) and Oracle Operational DB highlight critical scaling considerations for practitioners designing similar mission-critical systems.