hMailServer 6.2.1

Released 14 June 2026 6.2 series

This is not the current release. hMailServer 6.3.3 is the one to install unless you need this exact version.

Downloads for 6.2.1

Windows

Windows 10 (version 1607 or later) and Windows 11, or Windows Server 2016 and newer; 64-bit only. Run the installer as an administrator: it upgrades an installation older than this version in place, and it cannot go backwards — an older server refuses a database a newer one has upgraded, so back up the database and the data directory first. It is not Authenticode-signed, so Windows names an unknown publisher and SmartScreen warns before it will run it.

  • hMailServer-6.2.1-x64.exex64 · 79.5 MB
    Download
    SHA-2565f2627494ebb…8ea7a1cc

What’s new in 6.2.1

This release completes Track B4: deliverability and modern SMTP standards.

Full release notes for 6.2.1 2 sections

New in 6.2.1

  • PIPELINING (RFC 2920) advertised in EHLO.
  • SMTPUTF8 / EAI (RFC 6531/6532): internationalized addresses accepted and relayed.
  • ENHANCEDSTATUSCODES (RFC 2034): x.y.z codes on ESMTP replies.
  • DSN (RFC 3461/3464): RET/ENVID/NOTIFY/ORCPT accepted; per-recipient NOTIFY honored (NOTIFY=NEVER suppresses failure DSNs).
  • SRS (Sender Rewriting Scheme): HMAC-signed, reversible envelope rewrite on forwarding for SPF alignment; bounces decoded back to the original sender. Opt-in via [Settings] SRSEnabled/SRSSecret.
  • Per-IP and per-destination SMTP rate shaping via [Settings] MaxSubmissionsPerIPPerMinute / MaxOutboundPerDestinationPerMinute (both default off).

Fixes

  • Unicode::WideToMultiByte returned a trailing NUL that could corrupt DPAPI-protected stored secrets; now trimmed to the exact byte length.

All new features default to off / back-compatible. Builds clean (0 warnings, 0 errors); SMTP regression suite and in-server self-tests green.

Release facts

Version
6.2.1
Packages
1Windows, x86-64
Installer SHA-256
5f2627494ebb…8ea7a1cchMailServer-6.2.1-x64.exe

Every file in 6.2.1

Full SHA-256 of each file as recomputed on this server. Nothing in this release is signed — the signing workflow came later — so the hash above is this server’s own recomputation rather than a check against something the project signed.

FileWhat it isSizeSHA-256Signature
hMailServer-6.2.1-x64.exeWindows installer · x6479.5 MB5f2627494ebb94a1461ab67c4ed2a26d9c84d1914d1ae173ae3eef338ea7a1cc—