They agreed to share it, hiding from the users which network they were connected to, and nullifying the use of pseudo-domains like .uucp or second-level domains like gov.uk, thereby creating a practice that has been enforced ever since, and also applied in other countries.
Some hosts went so far as to try to "rewrite" the path, sending mail via "faster" routes—this practice tended to be frowned upon.
At the time, networks prevalent in the Brazilian academic setting were the BITNET ("Because It's Time NETwork"), the HEPnet ("High Energy Physics Network") and the UUCP ("Unix-to-Unix Copy Program").
For many early networks, such as UUCPNET, FidoNet and BITNET, lists of machines that were open relays were a core part of those networks.