E-Mail Distribution List Support
updated 12-JAN-1997
Electronic mail distribution lists can be broadly classified as either
local or global.
A local e-mail distribution list is one that you create for yourself
to make it easier for you to send a single e-mail to several different
addresses at once. When you create a local distribution list, you give
it a name of your own choosing, and then use this name as if it were an
address when sending e-mail. Normally a local distribution list resides
in your
own directory and can be accessed only by you. The return address of
the message is your own return address just
as it would be if you were sending
a message without using the list.
The best way to think of a local distribution
list is that it works pretty much the
same as if you had taken the time to enter each address manually
at the start of your message.
How you create a local distribution list depends upon the
particular e-mail
program that you use. The name that you assigned to your list may or
may not appear in the out-going message, again depending upon the
particular features of your e-mail program.
In any case it would be wise not to use
something derogatory, just to be safe!
A global list, more commonly known as a list server list,
is one that makes it easier for two or more
people to share an e-mail distribution list. In fact the most common
type of list allows anyone who is on the list to use it. Unlike a
local list, a list server list is assigned its own unique Internet
address. Often this address is used as the return address of any
mail message that was distributed via the list.
The name of the list is pretty much up to the owner of the
list, within in certain restrictions dictated by software and site
requirements.
A global distribution list typically requires the use of a
special software program generically known as a Mailing List Manager
(MLM) package. Such a package is also commonly called a
list server which should
not be confused, by the way, with
"LISTSERV" -- the brand name of a commercially
available MLM package.
Computing & Information Services (CIS) installs, maintains,
and supports a particular list server package called CREN ListProcessor
(or just ListProc for short). This server is available for use by
any current student, faculty, or staff member of the University of
New Hampshire. The local
ListServ documentation explains, in detail, the capabilities of this
package and how to access on-line vendor documentation on its use.
In general, a local list implemented with your particular e-mail
program makes sense for relatively small, informal lists intended
for your own use. Large lists, or lists that need to be shared
with more than one person are generally best done using a Global
distribution list supported by a Mail List Management (MLM) software
package like ListProc.
Here are some of the advantages and disadvantages of each approach.
Local Distribution Lists
- Advantages:
- Much easier to create, no application process is necessary.
A local list can be created, used a few times, and deleted
in less time than it would take just to apply for a global
list on a list server.
- Easier to maintain. A local list is created and maintained
either by using a built-in facility of your mail program, or
by creating files using your favorite text editor. A list
server list, in contrast, is controlled by exchanging e-mail
messages with the server program. This can be time consuming
and error prone.
- Disadvantages:
- Local lists are not really suitable for a discussion style
of list. This is because a
local list is more difficult to share. On a multi-user
machine such as the Central Unix systems and the Administrative
VAX systems, file protections can be used to allow other
people on that machine to access your local lists. This can be
difficult to set up initially and raises some security issues.
Sharing a local list with people not on
your machine is considerably more difficult and raises several
very serious security issues.
- A local list may not handle mail errors very well. For example
a Pine address book distribution list will fail to deliver
a message to most of the people on the list if even one of
the addresses is incorrect. This is a
known problem for which
there currently is no solution.
- Local lists become difficult to use with very large lists, i.e.
lists of over 50 addresses. Often the mailer will include the
list of all the addresses in the list as part of the message
header resulting in mail messages that have a page's worth of
header text but only a few lines of actual message content.
- More maintenance is required for a local list where addresses
are
being added and removed on a regular basis. A list server
list provides software automation that allows, for example,
people to add or remove themselves from the list.
Global (i.e. "list server") Distribution Lists
- Advantages:
- A list server list is ideal for a discussion group type of list.
once created, the list can be configured to take care of many
maintenance issues by itself. For example, people can add or
remove themselves from the list, and e-mail addresses that are
no longer valid can automatically be removed from the list by
the list server software. The list server will also automatically
send documentation about how to use the list to every new
subscriber as his or her address is added to the list.
- A global list is given it's own unique address on the Internet.
This allows the ownership of the list to be changed over the
life of the list without disruption since the list is not
exclusively associated with a particular personal e-mail
address. This also helps to separate list traffic from your
own e-mail traffic.
- A list server list can be operated in a variety of different
modes. For example, a list can be "open" allowing anyone
to post a message to the list, or "restricted" allowing only
subscribers to post. An "announcement" type of list allows
only the list owner to post, making this like a local list
in most respects but the return address is the list, not
the owner's own personal address. Finally a list can be
moderated, allowing anyone to submit a posting but allowing
the list moderator to control what actually is distributed.
A list server list can be set-up as any of these types
initially but then changed later as needs require.
- Disadvantages:
- Creating a list server list requires an application process.
This can cause some delays and fair amount of up-front work
to get your list started. It may also require you to use a name
for your list that was not your first choice because of
naming conflicts or server and policy requirements.
- Using a global server requires learning a new command language
for interacting with the list server. This amounts to having
to learn how to use yet another computer program.
- Adding and removing addresses from a list server list is not
as easy or intuitive as a local list. For even an experienced
list owner the process of adding or removing an address from the
list is more time consuming than for a local list.
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