Most early BBSes operated as stand-alone islands. Information contained on that BBS never left the system, and users would only interact with the information and user community on that BBS alone. However, as BBSes became more widespread, there evolved a desire to connect systems together to share messages and files with distant systems and users. The largest such network was FidoNet.
As is it was prohibitively expensive for the hobbyist SysOp to have a dedicated connection to another system, FidoNet was developed as a store and forward network. Private electronic mail (Netmail), public message boards (Echomail) and eventually even file attachments on a FidoNet-capable BBS would be bundled into one or more archive files over a set time interval. These archive files were then compressed with ARC or ZIP and forwarded to (or polled by) another nearby node or hub via a dialup Xmodem session. Messages would be relayed around various FidoNet hubs until they were eventually delivered to their destination. The hierarchy of FidoNet BBS nodes, hubs, and zones was maintained in a routing table called a Nodelist. Some larger BBSes or regional FidoNet hubs would make several transfers per day, some even to multiple nodes or hubs, and as such, transfers usually occurred at night or early morning when toll rates were lowest. In Fido's heyday, sending a Netmail message to a user on a distant FidoNet node, or participating in an Echomail discussion could take days, especially if any FidoNet nodes or hubs in the message's route only made one transfer call per day.
FidoNet was platform-independent and would work with any BBS that was written to use it. BBSes that did not have integrated FidoNet capability could usually add it using an external FidoNet front-end mailer such as FrontDoor, BinkleyTerm, InterMail or D'Bridge, and a mail processor such as FastEcho or Squish. The front-end mailer would conduct the periodic FidoNet transfers, while the mail processor would usually run just before and just after the mailer ran. This program would scan for and pack up new outgoing messages, and then unpack, sort and "toss" the incoming messages into a BBS user's local electronic mailbox or into the BBS's local message bases reserved for Echomail. As such, these mail processors were commonly called "scanner/tosser/packers."
Many other BBS networks followed the example of FidoNet, using the same standards and the same software. These were called FidoNet Technology Networks (FTNs). They were usually smaller and targeted at selected audiences. Some networks used QWK doors, and others such as RelayNet (RIME) and WWIVnet used non-Fido software and standards.
Before commercial Internet access became common, these networks of BBSes provided regional and international e-mail and message bases. Some even provided gateways, such as UFGATE, by which members could send/receive e-mail to/from the Internet via UUCP, and many FidoNet discussion groups were shared via Usenet. Elaborate schemes allowed users to download binary files, search gopherspace, and interact with distant programs, all using plain text e-mail.
As the volume of FidoNet Mail increased and newsgroups from the early days of the Internet became available, satellite data downstream services became viable for larger systems. The satellite service provided access to FidoNet and Usenet newsgroups in large volumes at a reasonable fee. By connecting a small dish & receiver, a constant downstream of thousands of FidoNet and Usenet newsgroups could be received. The local BBS only needed to upload new outgoing messages via the modem network back to the satellite service. This method drastically reduced phone data transfers while dramatically increasing the number of message forums.
FidoNet is still in use today, though in a much smaller form, and many Echomail groups are still shared with Usenet via FidoNet to Usenet gateways. Widespread abuse of Usenet with spam and pornography has led to many of these FidoNet gateways to cease operation completely.