To join the hardycacti_etc mailing list which discusses cold-hardy succulents, send to the address listproc@opus.scs.agilent.com the message:
subscribe hardycacti_etc Richard M. Nixon
but substitute your own name if it is not "Richard M. Nixon". You will then receive more information about how to post messages to the list and to get files from the archives.
Alternatively, there is an on-line form you can fill out.
In the list, discussions are carried on about all aspects of hardy succulent plants, including propagation, sources, and cultivation.
Bob Jewett