---
title: "hMailServer 6.0.0: the modernised baseline, and the build 4 installer fix"
url: https://www.hmailserver.co.uk/topic/28213/hmailserver-6.0.0-the-modernised-baseline-and-the-build-4-installer-fix
author: "Progressiverobot"
published: 2026-06-12T15:15:59.000Z
updated: 2026-06-12T15:15:59.000Z
category: "Announcements & releases"
tags: ["release","installer","tls","dns","windows"]
site: hMailServer Community Forum
---

# hMailServer 6.0.0: the modernised baseline, and the build 4 installer fix

6.0.0 is the first modernised release of the fork: 64-bit only, built with the VS2026 toolchain, with OpenSSL 4 and TLS 1.2 and 1.3 underneath. Build 4 is the production build, and it fixes the installer defect that made build 3 unusable on fresh installations.

**What the upgrade involved**

6.0 was 64-bit only. The installer dropped the obsolete 2015-era UCRT, which had been included in Windows since Server 2016 / Windows 10. Upgrade notes and the full feature list are in the README.

**The installer fix**

Build 3 bundled VS2019-era VC++ runtime DLLs. The service loaded those instead of the current ones and crashed at startup with an access violation in msvcp140.dll on fresh installations. Build 4 ships the matching v145 (14.51) runtimes. Build 3 also fixed MySQL/MariaDB database creation, which was a script line-ending problem, and bundles libmysql.dll.

**What 6.0 brought**

- OpenSSL 4, TLS 1.2 and 1.3
- MTA-STS and DANE, with in-process DNSSEC validation
- ARC sealing and Ed25519 DKIM
- ACME (Let's Encrypt) built in
- REST admin API and Prometheus metrics
- IMAP MOVE, ID and SPECIAL-USE
- PBKDF2 password hashing

The release was validated by the full regression suite: 898 of 898 tests passing, zero failures, run against a MariaDB (MySQL backend) instance, including live SpamAssassin, ClamAV with real EICAR detection, DMARC against live DNS, and TLS 1.2 and 1.3 end to end.

[Full release notes, checksums and signatures](https://www.progressiverobot.com/hmailserver-downloads/)