When registered to a list one may just read passing messages. This is a very good means to be aware of what is going on on a given topics. But when participating in a discussion some rules must be followed:
reply
feature of your e-mail interface. Depending on the listserv configuration a reply may go either to the list or to the sender. It is very inappropriate to answer to the list when the message becomes personal or too technical. Often the person who starts a discussion will summarize all the answers in a message which avoids numerous exchanges and disturbances to participants. Check the address before sending your answer!