Fidonet is governed in a hierarchical structure with designated coordinators at each level to manage the administration of FidoNet nodes. Local network coordinators are responsible for managing the individual nodes within their area (city or similar sized area). Regional coordinators are responsible for managing the administration of the network coordinators within their region (the size of a state, or small country). Zone coordinators are responsible for managing the administration of all of the regions within their zone. The world is divided into six zones, the coordinators of which elect one of themselves to be the "International Coordinator" of FidoNet.

Prior to the widespread use of the Internet. Fidonet used point-to-point transfers with analog-modem based telephone systems.

Fidonet Mail and Message Transfers

Fidonet used a proprietary protocol for "tossing" messages through the FidoNet network. In the analog modem based days, a BBS using a FidoNet "mail tosser" would call another BBS to send messages to that BBS. That BBS may be a local hub, a regional hub, or sent directly to destination BBS via a method called "crashmail". Typically a BBS would send messages once a day to a few times a day. To reduce the amount of telephone toll charges (long distance), a BBS would try to call a local BBS which then would try to call another local BBS, only using the long distance network sparingly as needed to reduce costs to the SysOps who paid for the phone bills. Message routing and addressing will be discssed in detail below.

Some BBS software included FidoNet mail tossing software, while other BBSes relied on third-party mail tossers. These will be discssed in detail below.

With the advent of the Internet, point-to-point FidoNet message delivery is becoming a thing of the past. There are now several methods of transferring messages via the Internet to hub or directly to BBSes without using the analog telephone network. Again, these will be discussed in detail below.

Netmail

Netmail is FidoNet terminology for the transfer of private message between people through the FidoNet network. The FidoNet system was responsible for routing the message from one system to the other (details below), with the BBS on each end being responsible for ensuring that only the intended recipient could read it. Due to the hobbyist nature of the network, any privacy between sender and recipient was only the result of politeness from the owners of the FidoNet systems involved in the mail's transfer. It was common, however, for system operators to reserve the right to review the content of mail that passed through their system.Netmail allowed for the "attachment" of a single file to every message. This led to a series of "piggyback" protocols that built additional features onto FidoNet by passing information back and forth as file attachments. These included the automated distribution of files, and transmission of data for Inter-BBS "Door Games".

Echomail

Echomail is the concept of networked message groups. BBS systems can "subscribe" to an Echomail conference (or "message forum") to send and receive messages based upon a particular topic. A message can be created on any BBS and received by any BBS who subscribes to it. These messages can be considered like pre-Internet Usenet or other distributed message conference concept. Echomail has been one of the more popular features of FidoNet. Echomail was so popular that for many users, Echomail was the FidoNet. Private person-to-person Netmail was relatively rare.

FidoNet is politically organized into a tree structure - the hierarchy consists of Zones, Regions, Networks, Nodes and Points broken down more-or-less geographically.

The highest level is the Zone, which is largely continent-based:

• Zone 1 is North America
• Zone 2 is Europe, ex-USSR (including Russia) and Israel
• Zone 3 is Australasia
• Zone 4 is Latin America (except Puerto Rico)
• Zone 5 is Africa
• Zone 6 is Asia (excluding Israel and the Asian parts of Russia, which are listed in Zone 2)

Each zone is broken down into regions, which are broken down into nets, which consist of individual nodes. Zones 7-4095 are used for other non-FidoNet networks which desire to use the same FidoNet protocol techology for their own networks. Using un-used zone numbers would ensure that each network would have a unique set of addresses, avoiding potential routing conflicts and ambiguities for systems that belonged to more than one network.

FidoNet Address Structure

FidoNet addresses explicitly consist of a Zone number, a Network number (or region number), and a Node number. They are written in the form Zone:Network/Node. For example, consider a node located in Tulsa, Oklahoma, USA with an assigned node number is 918, located in Zone 1 (North America), Region 19, and Network 170. The full FidoNet address for this system would be 1:170/918. The region was used for administrative purposes, and was only part of the address if the node was listed directly underneath the Regional Coordinator, rather than one of the networks that were used to divide the region further.

Fidonet provides a method of keeping track of every BBS on FidoNet. This is called a "Nodelist". This list contains a list of all BBS systems that are currently on Fidonet ? public systems, private systems and "down" (i.e. currently not operational) systems.
The nodelist is updated weekly, to avoid unwanted calls to nodes that had shut down, with their phone numbers possibly having been reassigned for voice use by the respective telephone company. The nodelist is updated weekly with up to date BBS modem numbers and/or Telnet addresses. Regional coordinators send updates via a process called "Nodediff" and a new nodelist is generated based upon the nodediffs that are created.

Routing of FidoNet mail

In a theoretical situation, a node would normally forward messages to a hub. The hub, acting as a distribution point for mail, might then send the message to the Net Coordinator. From there it may be sent through a Regional Coordinator, or to some other system specifically set up for the function. Mail to other zones might be sent through a Zone Gate. For example, a FidoNet message might follow the path:

1:170/918 (node) to 1:170/900 (hub) to 1:170/0 (net coordinator) to 1:19/0 (region coordinator) to 1:1/0 (zone coordinator). From there, it was distributed 'down stream' to the destination node(s).

Part of the objective behind the formation of local nets was to implement cost reduction plans by which all messages would be sent to one or more hubs or hosts in compressed form (usually PKZIP); one toll call could then be made during off-peak hours to exchange entire message-filled archives with an out-of-town uplink for further redistribution. In practice, the FidoNet structure allows for any node to connect directly to any other, and node operators would sometimes form their own toll-calling arrangements on an ad-hoc basis, allowing for a balance between collective cost saving and timely delivery.

For instance, if one node operator in a network offered to make regular toll calls to a particular system elsewhere, other operators might arrange to forward all of their mail destined for the remote system, and those near it, to the local volunteer. Operators within individual networks would sometimes have cost-sharing arrangements, but it was also common for people to volunteer to pay for regular toll calls either out of generosity, or to build their status in the community.

This ad-hoc system was particularly popular with networks that were built on top of FidoNet. Echomail, for instance, often involved relatively large file transfers due to its popularity. If official FidoNet distributors refused to transfer Echomail due to additional toll charges, other node operators would sometimes volunteer. In such cases, Echomail messages would be routed to the volunteers' systems instead. As the FidoNet system was best adapted to an environment in which local telephone service was inexpensive and long-distance calls (or intercity data transfer via packet-switched networks) costly, it fared somewhat poorly in countries such as Japan, where even local lines are expensive. FidoNet was only moderately successful in countries such as France, where tolls on local calls and competition with Minitel or other data networks traditionally limited its growth.

Points

As the number of messages in Echomail grew over time, it became very difficult for users to keep up with the volume while logged into their local BBS. Points were introduced to address this, allowing technically savvy users to receive the already compressed and batched Echomail (and Netmail) and read it locally on their own machines.

To do this, the FidoNet addressing scheme was extended with the addition of a final address segment, the point number. For instance, a user on the example system above might be given point number 10, and thus could be sent mail at the address 1:170/918.10.

Points are relatively rare in Zone 1 (North America) but are more poular in Europe (Zone 2) and elsewhere since even a local phone call ususally costs money, unlike most of North America where local calls are usually "free".

FidoNet mail tossing is the "back end" software to make all the file transfers happen. FidoNet can either have intergrated tossing (built into the BBS software) is external and relied upon third-party software to performthese transfers. External software has been used more often, allowing for greater flexibility and allowing the BBS authors to concentrate on the BBS software not worry about FidoNet.

Third-party mail tossing software usually was "in front" of the BBS and answered analog modem calls. When it detected an incoming FidoNet transfer, it would establish a connection with the mail tossing software at theopposite end and perform file transfers (originally with XMODEM, later using ZMODEM as the standard). Once a message was transferred, usually the mail tossing software would run a "batch file" to send the messages to the host BBS.

When outgoing mail was waiting on the local BBS, the mailer software would attempt to send it from time to time by dialing and connecting to other systems who would accept and route the mail further. Due to the costs of toll calls which often varied between peak and off-peak times, mailer software would usually allow its operator to configure the optimal times in which to attempt to send mail to other systems.

When a human caller called a BBS, the human caller would typically have to either wait for a "timeout" or press a set of keys (the Escape key or other set of keys) to "escape" from the FidoNet mail tossing software. The program would then pass the human caller to the host BBS to log on and to interact with the BBS itself (read and post messages, play games, transfer files, etc.)

A scanner/tosser application, such as FastEcho, FMail, TosScan and Squish, would normally be invoked when a BBS user had entered a new FidoNet message that needed to be sent, or when a mailer had received new mail to be imported into the local messages bases. This application would be responsible for handling the packaging of incoming and outgoing mail, moving it between the local system's message bases and the mailer's inbound and outbound directories. The scanner/tosser application would generally be responsible for basic routing information, determining which systems to forward mail to.

In the modem days, FidoNet mailers such as FrontDoor, Intermail, and D'Bridge were common. These can still be used today using "virtual modems" for those SysOps who are connected to the Internet using Telnet.

Modern Fidonet Mail Tossing via the Internet

With the advent of the Internet, programs have been developed to allow for "off-line" transfers that do not directly "dial-up" a BBS. Such programs are popular because they do not interfer with human callers and can be invoked at any time for a direct connection (typically using a special TCP/IP port that does not interfer with Telnet). Pouplar mailers for Windows include Argus, Radius, and Taurus. A popular open source FidoNet Mailer for Linux is BinkD. These can go to a local hub, a regional hub or any BBS that uses similar protocols -  including direct BBS "crashmail". 

While the use of FidoNet has dropped dramatically compared with its use up to the mid-1990s, it is still particularly popular in Russia and former USSR. Some BBSes, including those that are now available for users with Internet connections via Telnet, also retain their FidoNet netmail and echomail feeds. There are also web sites that offer the full FidoNet feed from your web browser. Some of FidoNet's echomail conferences are available via gateways with the Usenet news hierarchy. In the early days of the Internet, there were gateways to transfer E-mail to and from the Internet. Because of large amounts of spam, these have been shut down.

Argus
http://www.ritlabs.com/argus/ 
Last updated: Mar. 2001

BinkleyTerm XE
http://btxe.sourceforge.net    
Last updated: Nov. 1998

BinkD
http://2f.ru/binkd/
Last updated: July 2000

Fido-Deluxe IP
http://www.fido-deluxe.de.vu
Last updated: Sep. 2003

FrontDoor (Definite Solutions)
http://www.defsol.se         

Husky Project
http://sf.net/projects/husky/
Last updated: Sep. 2003

Radius (Argus clone)
http://radius.pp.ru          
Last updated: Jan. 2005

Taurus (Radius clone)
http://www.fidotel.com/taurus
Last updated: Oct. 2004

Wildcat Platinum Express (Wildcat BBS only)
http://www.santronics.com
Last updated: Apr. 2004

Fmail
http://fmail.nl.eu.org

Squish (part of Maximus)
http://maximus.sourceforge.net/

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