Here are the mailing list addresses for sam, rc, and es. 9term is generally discussed on the sam-fans list.
subscriptions: sam-fans-request@hawkwind.utcs.utoronto.ca
messages: sam-fans@hawkwind.utcs.utoronto.ca
subscriptions: rc-request@hawkwind.utcs.utoronto.ca
messages: rc@hawkwind.utcs.utoronto.ca
subscriptions: es-request@hawkwind.utcs.utoronto.ca
messages: es@hawkwind.utcs.utoronto.ca
Mailing list archives are all on ftp.sys.utoronto.ca.
The mailing list for Plan 9 is 9fans@cse.psu.edu , which is the list itself, and 9fans-request@cse.psu.edu . This latter address is an automated mail server that will reply with a message telling you how to subscribe. The server also manages the archives. According to Scott Schwartz, the manager, “You can get a list of available files by sending e-mail to Majordomo@cse.psu.edu with index 9fans as the message body. Files can be retrieved with get plan-9fans filename. If you want a complete list of available commands send help to majorodomo@cse.psu.edu.”