This was a beta build of the 6.0 line. 6.0.0 was the production release. Nothing here should be installed today. Build 3 shipped VC++ runtime DLLs that did not match the toolset the binaries were built with, and the service crashed at startup on fresh installs. This build corrects the installer payload. The detail: hMailServer.exe is built with v145 (14.51), but build 3 bundled VS2019-era (14.25) VC++ runtime DLLs app-local in Bin\. Those app-local copies were loaded instead of the system runtimes, and the service died at startup with 0xC0000005 in msvcp140!mtx_do_lock, reached via boost regex and std::mutex. Fresh installs were the ones affected. Changes in this build: The installer now ships Microsoft.VC145.CRT (14.51.36231), matching the build toolset. The stale Microsoft.VC142.CRT payload has been removed. The bundled 2015-era UCRT has been removed. It has been in-box since Server 2016 and Windows 10. build/run-tests.ps1: fixed a stdout/stderr pipe deadlock in the test runner. The full regression gate ran against MariaDB on the MYSQL backend: 898 of 898 passed. Full release notes, checksums and signatures