This is different or so it appears from Internet chess.
Some may have membership fees.
SchemingMind.com - Internet Correspondence Chess Club
CORRESPONDENCECHESS.COM - The place to be if you are interested in cc!
CCCA HomePage
Correspondence Chess League of America
ICCF - The International Correspondence Chess Federation - Home
International Correspondence Chess Federation - US Main Page
Correspondence Chess News
Free Internet Chess Games Server, Poker & Go online, news and forums
Online Chess
Correspondence Chess - Caissa's Web
World Correspondence Chess Federation
Ralph Marconi's Chess Page-Main Page
Note that many sites have disappeared.
The above appear to be operational.
SNAIL MAIL SITES:
Correspondence Chess@Everything2.com
Correspondence Chess League of America
CORRESPONDENCE CHESS DOWNLOADS:
Free and Shareware products.
Free correspondence chess Download - correspondence chess Mac Software
(The above are for Macintosh and Mac Intel computers.
For Window computers & cross platforms:
correspondence chess Software - Free Download correspondence chess