What is an email list?  It is a list of folks who share at least one common interest/theme.  They subscribe to the list.  Anyone on the list can ask or answer questions.  Though sharing many things with a bulletin board format, this is ran through your email.  When anyone sends email to the list, everyone gets a copy in their inbox.  Two places to start your email list search is on US Gen Web and http://egroups.yahoo.com.