(from Wikipedia)

MHSnet is a store-and-forward Message Handling System for wide area
networks. MHSnet and its precursor, SUN3, were used to implement the
Australian Computer Science network, commonly known as ACSnet, which
connected Australia's Universities to each other and to ARPANET.

MHSnet was originally developed at the University of Sydney by Piers
Lauder and Bob Kummerfeld and was originally known as SUN3 (Sydney
University Network version 3). Technically, it is similar in concept
to UUCP in that it enabled the transfer of email, Usenet, and files in
an efficient manner over non-dedicated links. In addition, it supported
dynamic routing and a hierarchical name space avoiding the limitations
of hardwired network addresses.

MHSnet was a key technology in the introduction of Internet access in
Australia. Due to the prohibitive costs of telecommunications structure,
and the small amount of bandwidth available both internally and to other
countries, MHSnet provided a system that could more efficiently utilise
network resources. Gateways between ACSnet and the Internet were provided
by many universities, and access to non-academic users was granted in
the early 1990s.

In 1989, with the introduction of AARnet which directly connected
Australia's Universities to the Internet, the ACSnet and MHSnet became
obsolete.
