CSNET

ARPANET was reserved for sites funded by the US Department of Defense, which left most computer science departments on the outside looking in. In 1981 Larry Landweber at the University of Wisconsin assembled a group that won National Science Foundation money for an alternative. CSNET connected departments however they could afford it: leased lines for the well-funded, X.25 for the middle tier, and PhoneNet for everyone else — mail batched up and relayed over ordinary dial-up modems.

The first email to reach Germany arrived over CSNET, at the University of Karlsruhe in 1984. More importantly, it proved a network could be run by the NSF rather than the military, which led straight to NSFNET. CSNET merged with BITNET in 1989 and shut down two years later.