Mercury Mail Transport System

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Mercury Mail Transport
Developer(s) David Harris
Stable release
4.80 / September 1, 2015 (2015-09-01)
Operating system Microsoft Windows
Type E-mail server
License Donationware/shareware

Mercury Mail Transport System (Mercury MTS) is a standards-compliant donationware for non-commercial and personal use and shareware for other uses with 60-day free evaluation period (was freeware prior to January 2007) mail server developed by David Harris, who also develops the Pegasus Mail client.

There are two versions of Mercury with similar functionality. One, Mercury/32, is a Win32 application running on all 32-bit versions of Microsoft Windows from Windows 98 and Windows NT4 to the latest (as of August 2009) Windows Vista and Windows Server 2008 (Windows XP or Windows Server 2003 are recommended). The other is a set of NetWare Loadable Modules (NLMs) which runs on all versions of the Novell NetWare network operating system (NOS) from 3.x to 6.x (current as of August 2009). Either version can act as a mail server for a LAN; both have additional support for some NetWare LAN features.

Mercury is a fully independent mail server and can provide email services to all standards-compliant email clients, such as Eudora or Microsoft Outlook. Both versions of Mercury are highly modular, allowing support for different sets of Internet protocols to be installed as required. Mercury can also be installed tightly integrated with Pegasus Mail. The combination of Pegasus/Mercury is similar to the mail aspects of Microsoft Outlook/Microsoft Exchange Server. Mercury was originally developed to handle mail, both internal and external, on Netware servers in either bindery or NDS mode; Mercury ran on the system server, and integrated with Pegasus mail running on MS-DOS or Windows workstations.[1]


Mercury is extremely standards-compliant, supporting all major Internet mail-related protocols including SMTP (for both sending and receiving mail), POP3 and IMAP. The Win32 version also supports a dialup connection. Both versions have many features, with especially powerful support for managed mailing lists. Mercury is intended to be largely unobtrusive and needs little ongoing maintenance.

The installation process is one of the most simple tasks. It takes less than a minute. After a few clicks, the software is installed and ready to be used. At this point, the user must indicate the domain parameter to be used. The user list is manually administered. There is no limit in numbers of users declared. A single directory holds users storage locations, so to do a backup just copy the "mail" directory and it will copy all users' data.

Also, a standard anti-virus could be used. After a mail is received, two files are created. When these files are finally written to disk, a simple antivirus engine could scan it. There is CLAMAV antivirus engine supplied, to be used as desired.

The software has an enormous variety of configurations. Using proper care, the server could be very secure. The relay control is very effective, and the ability to filter mails based in many rules, making it very efficient. Could use blacklist/whitelist technology. There are included tools to reduce spam effects.

Protocols supported[edit]

  • SMTP (server, relay-based client and full end-to-end delivery client)
  • POP3 (server and distributing client)
  • IMAP4rev1 (with multiple simultaneous access to the same mailbox)
  • PH (server, for directory lookups)
  • Finger (server, for directory lookups)
  • PopPass (server, for remote password changing)
  • HTTP (server, for web-based mailing list management)
  • SSL (Secure sockets layer) on SMTP, POP3 and IMAP servers
  • Mercury/32 4.73 can run as a MS Windows service


Mercury/32, while not open source software, can be extended by anyone as the development documentation is free and publicly available at the pmail community. Below are some well known extensions, some bundled with Mercury/32.

Development status of Mercury Mail Transport System[edit]

On 19 June 2009 David Harris announced on the Pegasus Mail site that all development of Pegasus Mail and the associated Mercury program could only continue if sufficient users would commit to donating US$50 annually;[2] on 21 July 2009 he said that there had been a good start [1].

New versions of both programs have been released since. Developer David Harris in April 2017 said that, despite no news being published for some time, both Pegasus Mail and the Mercury transport system were under active and major further development.[3]


  1. ^ Internet mail: Another Internet gateway for Pegasus Mail -- Mercury. Mercury is an Internet/Novell mail gateway program that is designed to work in conjunction with Pegasus Mail ...
  2. ^ David Harris (August 2010). "An open letter to my user community". Retrieved 2 April 2017.  Latest update August 2010.
  3. ^ David Harris (April 2017). "Pegasus Mail and Mercury Developer News". Retrieved 2 April 2017. 

External links[edit]