After mail has been read it may be forwarded, a reply may be made, it may be deleted, or saved for future reference. Telnet allows you to access a remote computer, read files and data, and use its services as if you were connected to it directly. You put your own name on a list and remove your name when you no longer want to receive mail from that list. One address is for the clerical robot program that takes care of subscribe, postpone, and unsubsribe requests. A second address is used to talk with all other people on the list.
Some lists have a third address, for the human being who moderates the list.
This is the address you can write to get clarification if the list confuses you, won't react as expected, or offends you. When you first subscribe to a list, the clerical robot sends you back a message to say you are subscribed to the list. The message also includes other e-mail addresses for the list, and commands you need to use to unsubscribe, put mail on hold, etc. By the time you need to use its information, you probably won't remember the commands. Be aware that some lists are very active and receive a lot of mail.