
Understanding Mailing Lists
by Harley Hahn (© 2000)

A mailing list is a system by which a
group of people can have a discussion via
electronic mail. The idea is that a person
can send a message to one central address.
That message is then processed by a program
which automatically sends a copy of the
message to everyone on the list. Thus, once
you join a mailing list, you will
automatically receive copies of all the
messages that anyone sends to the central
address. These messages will be sent to
your electronic mailbox.
When you join a mailing list, we say you
subscribe to that list. To leave the list
-- that is, to stop receiving mail -- you
unsubscribe. Although we use the words
"subscribe" and "unsubscribe", there is no
cost involved. You can join -- and quit --
as many mailing lists as you want for free.
However, if you join too many, your mailbox
will be flooded with so much mail, you won't
have time to read it.
Subscribing and unsubscribing to a mailing
list is easy. Each list has a special
administrative address. All you have to do
is send a message to that address saying
that you want to subscribe or unsubscribe.
A program (not a person) will read and
process the message, and carry out your
request.
There are three main types of mailing list
systems. They are called Listserv, Listproc
and Majordomo. Subscribing and
unsubscribing with each is almost the same.
The is only one small difference when you
subscribe to a Majordomo list (which I will
explain below).
Let's look at an example taken from my book
Harley Hahn's Internet & Web Yellow Pages.
In the "Animals and Pets" section of the book,
there is an item called "Horses".
One of the resources under this item is a
mailing list. Here is the information:

Listserv Mailing List:
List Name: equine-l
Subscribe to: listserv@psuvm.psu.edu

What can we tell about this list?
First, we see that this is a Listserv
mailing list, as opposed to Listproc or
Majordomo.
Second, each mailing list has a name. The
name of this list is equine-l.
Notice the two characters -l
at the end of the name. In the olden days
before the Internet), it was necessary to know
if an name belonged to a person or a mailing
list. Thus, mailing lists were given names
that ended with -l. The
letter l (L) stands for "list".
On some systems, this is still the custom.
That is why this name, equine-l,
ends with -l.
The third piece of information we see is the
address to which we would send mail to
subscribe. In this case, it is

listserv@psuvm.psu.edu

This is the address of the program that
administers the list.
When you send a
message to this address, your message is not
seen by a person. Everything is done
automatically by the Listserv program. It
will read your message, figure out what you
want, and respond appropriately.
There are many commands you can send to a
Listserv program (and the same goes for
Listproc and Majordomo). I will describe
four.

Getting Information About a Mailing List

Before you subscribe to a mailing list, you
should always send a request to the mailing
list program asking for information about
that list. This will help you make sure you
really want to subscribe, as well as alert
you to any special considerations about the
list. To request such information, send an
email message to the administrative
(subscription) address. The subject of the
message doesn't matter: it will be ignored.
In the body (main part) of the message, put
a single line consisting of the word
info followed by the name of
the list.
For example, in this case, you would email a
message to:

listserv@psuvm.psu.edu

The subject of the message could be
anything. In the body of the message, you
would type the single line:

info equine-l

Now wait until you receive an email reply with
some information. Sometimes this takes only
a few minutes, sometimes longer. When you
receive the reply, read the information and
see if you still want to subscribe. (There
will be a lot of technical information you
can ignore.)

Subscribing to a Mailing List

After you find out about mailing list,
you can subscribe by sending a
one-line message to the same administrative address.
This message should have the word
subscribe, followed by the
name of the list, followed by your first
and last names. You do not need to specify
your email address. The program at the
other end will pick it up automatically.
Let's say your name is Bart
Bunzlehammer. To subscribe to the
equine-l mailing list,
send a one-line message to the address:

listserv@psuvm.psu.edu

The subject of the message doesn't matter.
In the body of the message, you type the
single line:

subscribe equine-l Bart Bunzlehammer

When the message is received, the Listserv
program will automatically subscribe you to
the list. From now on, any messages sent to
the list will be sent to you as well.
Hint: For security reasons, some mailing
list programs require you to confirm that
you really want to join the list (just in
case some friend has snuck over to your
computer while you were away and sent in a
subscription to a mailing list). If this is
the case, you will be sent instructions on
how to confirm. Usually, it is as simple as
replying to a message and saying "ok".

Unsubscribing to a Mailing List

You can unsubscribe to a mailing list at any
time. Just send a one-line message to the
administrative address with the word
unsubscribe, followed by the
name of the list. You do not need to include
your name or your email address. In our
example, you would send a message to the address:

listserv@psuvm.psu.edu

The subject of the message doesn't matter.
In the body of the message, type the single
line:

unsubscribe equine-l

For a Listproc mailing list, everything
works exactly the same. For a Majordomo
mailing list, there is only one difference:
when you subscribe, you do not have to
specify your first and last name.
The final command I want you to know about
is help. Listserv, Listproc
and Majordomo systems have more commands than
info, subscribe
and unsubscribe. To learn about
these commands, send a one-line message to
the administrative address with the single
word help. For example, you can send a
message to the address:

listserv@psuvm.psu.edu

The subject of the message doesn't matter.
In the body of the message, type the single
line:

help

Once you belong to a list, the question
arises, how do you send messages to everyone
on the list? You do not send messages to
the administrative address: that is only for
subscribing, unsubscribing and so on.
Rather, you send messages to the list
itself. The list's address consists of the
name of the list, followed by the name of
the computer.
In our example, the name of the list is
equine-l. The name of the
computer is psuvm.psu.edu.
Thus, to send a message to the list itself
(that is, to all the people on the list),
you would mail to:

equine-l@psuvm.psu.edu

Each time you send a message to this
address, it will be sent automatically to
everyone on the list.
So remember, when you want to unsubscribe,
do not send the unsubscribe message to this
address. All administrative requests go to
the administrative address (where they are
handled automatically by a program).

Summary

For reference, the following summary covers what
I have explained in this article.
(Notice that, with one exception, all three systems
-- Listserv, Listproc and Majordomo -- work the same.
The exception is: when you subscribe to a Majordomo
mailing list, you do not specify your first and last name.)

To request information about a mailing list,
or to subscribe or unsubscribe, send mail to
the administrative (subscription) address
for the list. For example:

listserv@psuvm.psu.edu
majordomo@massey.ac.nz
listproc@cornell.edu

To request information about the list,
use the command:

info listname

To request general help information, use
the command:

help

To subscribe to a list with Listserv and Listproc,
use the command:

subscribe listname firstname lastname

To subscribe to a list with Majordomo, use
the command:

subscribe listname

To unsubscribe to a list, use the command:

unsubscribe listname