The official documentation is no longer hosted online. However, historical snapshots from the Lotus Developer Domain (now a HCL wiki) are preserved on the Wayback Machine (web.archive.org).
Released by IBM, version 8.5.3 offered crucial improvements in stability, performance, and application development (XPages) over its predecessors. While the Lotus Notes client was historically a 32-bit application, IBM introduced 64-bit support for specific components within the 8.5.x lifecycle, specifically targeting Windows 64-bit environments, allowing it to handle larger memory requirements better than 32-bit versions. Key Features of 8.5.3 lotus notes client 8.5 3 64 bit download