---
title: "hMailServer 6.0.0-B1: first regression-validated build of the modernised 6.0 line"
url: https://www.hmailserver.co.uk/topic/28211/hmailserver-6.0.0-b1-first-regression-validated-build-of-the-modernised-6.0-line
author: "Progressiverobot"
published: 2026-06-12T14:06:21.000Z
updated: 2026-06-12T14:06:21.000Z
category: "Pre-release builds"
tags: ["prerelease","schema","tls","windows","upgrade"]
site: hMailServer Community Forum
---

# hMailServer 6.0.0-B1: first regression-validated build of the modernised 6.0 line

This was a beta build of the 6.0 line. 6.0.0 was the production release. Nothing here should be installed today.

This is the first build of the modernised 6.0 line to clear the full regression suite: 898 tests, 895 passed, 0 code failures.

**What the upgrade involved**

Database version was 6001. Upgrade from 5.7 was supported via DBUpdater.

Toolchain for this build: VS2026 (v145), OpenSSL 4.0.1, Boost 1.91, PostgreSQL 18.3 libpq, .NET Framework 4.8.1.

What 6.0 brings in:

- MTA-STS and DANE/DNSSEC outbound TLS policy, TLS-RPT reporting, TLS 1.2/1.3 defaults.
- ARC sealing, DMARC, Ed25519 DKIM.
- ACME (Let's Encrypt) with auto-apply.
- REST admin API, and an Administrator dashboard with TOTP 2FA.
- MTA-STS, autoconfig and autodiscover hosting.
- Prometheus metrics and JSON logging.
- PBKDF2 password hashing with transparent rehash.
- IMAP MOVE, ID and SPECIAL-USE, plus 8BITMIME.

Fixed in this build: a latent `CStdStr::FormatV` buffer-count bug that crashed the service.

Validation ran with live SpamAssassin (JAM Windows build), ClamAV 1.5.2 and all optional features enabled. The three non-passing tests are environment-bound rather than code defects. Two require an unfiltered DNS resolver for SURBL test queries, and one requires the service-based SpamAssassin variant.

Installation is via the installer, against the internal database (SQL CE 4.0) or an external MySQL, MSSQL or PostgreSQL instance. IMPLEMENTATION-NOTES.md carries the feature and INI reference.

Licensed AGPLv3. Based on hMailServer by Martin Knafve.

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