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Hmailserver admin.PNG
hMailServer Administrator Screenshot
Developer(s) Martin Knafve
Initial release 2002; 15 years ago (2002)
Stable release
5.6.4 (Build 2283)[1] / 9 July 2015; 18 months ago (2015-07-09)
Written in C++, C#
Operating system Microsoft Windows 2000/XP/2003/Vista/2008 (v4.0/v5.0)
Platform Windows
Type Mail transfer agent
License AGPL (previously proprietary)[2]

hMailServer is a free email server for Windows created by Martin Knafve. It runs as a Windows service and includes administration tools for management and backup. It has support for IMAP, POP3, and SMTP email protocols. It can use external database engines such as MySQL, MS SQL or PostgreSQL, or an internal MS SQL engine to store configuration and index data. The actual email messages are stored on disk in a raw MIME format. It has active support and development forums.

Common features such as multiple-domain support, aliases, catch-all and basic mailing lists are present. Users can be authenticated both against the local hMailServer user system and against an external Active Directory.


hMailServer offers a number of different AntiSpam mechanisms:


hMailServer has built in support for ClamWin/ClamAV. It's possible to execute any command line virus scanner.

Other features[edit]

  • Domain and account signatures (for legal and advertising footers)
  • Server side rules (rules for individual accounts available in v5)
  • Retrieval of messages from external POP3 accounts
  • Quotas on domain, mailbox, and individual message sizes
  • Plus addressing (using + to make a virtual alias for an account specific to a task, as seen in Gmail)
  • Attachment blocking (based on attachment extension)
  • Custom SMTP routes for specific domains (can be used to set up MX backup, forwarding and more)
  • API (it's possible to write hMailServer scripts using VBScript and JScript)
  • Built-in support for SSL



The hMailServer project was started in 2003. Up until 2008 and version 4, the project was licensed under the GPL. Versions 5.0 to 5.3 were proprietary.[2] Since version 5.4, hMailServer is licensed under the GNU AGPL 3,.[3][4]
The current version of hMailServer appears to be open source again [5] This is also noted on the hMailServer home page.[6]

See also[edit]


  1. ^ Martin Knafve. "Free open source email server for Microsoft Windows". hMailServer. Retrieved 2016-04-21. 
  2. ^ a b " Functionality". Retrieved 2012-03-05. hMailServer 4 and earlier versions are licensed as open source under the GPL license. Later versions of hMailServer (version 5 and later) are still free of charge but closed source. 
    Martin Knafve (2007-08-02). "A few different reasons.. [why version 5 is closed source]". Hmailserver-forums. Retrieved 2012-03-05. 
  3. ^ Martin Knafve. "Free open source email server for Microsoft Windows". hMailServer. Retrieved 2016-04-21. 
  4. ^ "Archived copy". Archived from the original on February 26, 2014. Retrieved February 20, 2014. 
  5. ^ "hmailserver 路 GitHub". Retrieved 2016-04-21. 
  6. ^ Martin Knafve. "Free open source email server for Microsoft Windows". hMailServer. Retrieved 2016-04-21. 

External links[edit]