Skip to content
  • Categories
  • Recent
  • Popular
  • Tags
  • Users
  • Groups
  • Documentation
  • Downloads
  • Report a bug
  • Commercial support
Skins
  • Light
  • Brite
  • Cerulean
  • Cosmo
  • Flatly
  • Journal
  • Litera
  • Lumen
  • Lux
  • Materia
  • Minty
  • Morph
  • Pulse
  • Sandstone
  • Simplex
  • Sketchy
  • Spacelab
  • United
  • Yeti
  • Zephyr
  • Dark
  • Cyborg
  • Darkly
  • Quartz
  • Slate
  • Solar
  • Superhero
  • Vapor

  • Default (No Skin)
  • No Skin
Collapse
hMailServer Community Forum
hMailServer 6.3.3 — signed 15 September 2026, Windows and Linux, database schema 6040, and a drop-in upgrade from any 5.x install.Download 6.3.3 Documentation
  1. Support and discussion for hMailServer
  2. Announcements & releases
  3. hMailServer 6.2.1: PIPELINING, SMTPUTF8, DSN and SRS

hMailServer 6.2.1: PIPELINING, SMTPUTF8, DSN and SRS

Scheduled Pinned Locked Moved Announcements & releases
releasesmtpbugfix
1 Posts 1 Posters 2 Views 1 Watching
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • P
    P
    Progressiverobot
    hMailServer Team
    wrote on last edited by
    #1

    6.2.1 completed Track B4, the deliverability and modern SMTP standards work. It added four ESMTP extensions, SRS for forwarded mail and SMTP rate shaping.

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

    One fix: Unicode::WideToMultiByte returned a trailing NUL that could corrupt DPAPI-protected stored secrets. The result is now trimmed to the exact byte length.

    Everything new here defaults to off and is back-compatible, so the release changed nothing about an existing configuration until a setting was turned on. The build was clean, 0 warnings and 0 errors, with the SMTP regression suite and the in-server self-tests green.

    Full release notes, checksums and signatures

    1 Reply Last reply
    0

    Hello! It looks like you're interested in this conversation, but you don't have an account yet.

    Getting fed up of having to scroll through the same posts each visit? When you register for an account, you'll always come back to exactly where you were before, and choose to be notified of new replies (either via email, or push notification). You'll also be able to save bookmarks and upvote posts to show your appreciation to other community members.

    With your input, this post could be even better 💗

    Register Login
    Reply
    • Reply as topic
    Log in to reply
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes


    • Login

    • Don't have an account? Register

    • Login or register to search.

    hMailServer Community

    The community support forum for hMailServer — the free, open-source mail server for Windows and Linux — maintained by Progressive Robot Ltd. The software is AGPL-3.0 and stays that way; this is where it is discussed, debugged and documented.

    The software

    • Documentation
    • Downloads
    • hMailServer 6.3
    • Source on GitLab

    Getting help

    • Forum rules
    • About this forum
    • Support plans
    • Pay monthly support
    • Talk to Progressive Robot

    Legal

    • Privacy policy
    • Terms and conditions
    • Cookie policy

    Progressive Robot Ltd · 220 Chester Business Park, Heronsway, Chester, Cheshire CH4 9GB, United Kingdom · +44 (0)1244 911212 · [email protected] · VAT 506152326

    Powered by NodeBB

    • First post
      Last post
    0
    • Categories
    • Recent
    • Popular
    • Tags
    • Users
    • Groups
    • Documentation
    • Downloads
    • Report a bug
    • Commercial support