Section 4 Mailing List Types

There are three main types or styles of mailing lists, each with its own advantages for specialized use. Setting specific keywords to certain values and then editing various templates creates different types of mailing lists. The style of list will best determine the particular keywords and their settings in your list header. Your LISTSERV maintainer will be able to create a list based on the style you want or need. When requesting a new list, make sure you tell your LISTSERV maintainer what style of list you want. The three major types of lists are:

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One-Way Announcement – The owner(s) and/or editor(s) of the list are the only people who are allowed to send messages to the subscribers. The communication flows one way – from the list administrators to the list subscribers. This type of list is primarily used for newsletters, product announcements, and dissemination of information that does not require feedback from the subscriber.

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Two-Way Discussion – The list administrators and the list subscribers are both permitted to post messages to the list. The communication flows two ways - between the administrators and the subscribers, and back and forth between different subscribers. This type of list is primarily used for discussion groups engaged in the exchange of ideas and information centered on a specific topic.

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Moderated – This type of discussion list has an editor or editors who review all incoming messages. The editor can then decide to allow the message to be sent to all the subscribers on the list, or not allow the message to be posted to the list. Moderated lists can be used to control the discussion by keeping off topic, inflammatory, or otherwise inappropriate messages from the reaching subscribers.

There are other types of lists, for example you can use a list as an “auto-responder”. The three types listed here are the most common. See the List Owner Manual for LISTSERV for more information on other list types.

4.1 One-Way Announcement Lists

One-way announcement lists or newsletters are types of lists where subscribers only receive information and do not interact with the other list members. This type of list is most commonly used for delivering news and media publications, company newsletters and any other types of announcements. For example, the “LISTSERV at Work” newsletter (see http://www.lsoft.com/news/newsletter-us.asp) is sent quarterly to keep the L-Soft community informed and up-to-date with the company's latest developments. One-way lists are similar to print newspaper subscriptions. They often have large numbers of subscriptions and people sign on and off the list as they wish. Set up an announcement list by using one of the following sets of keywords.

Table 4-1 Keywords for an Announcement Style List

Keyword and Suggest Value	Description
Send= Owner,Confirm	Only addresses listed in the Owner= keyword can post to the list. Non-owner addresses attempting to post receive a non-customizable rejection message.
Send= email-address,Confirm	Only the specified e mail address is allowed to post to the list. The sender is required to confirm the post. All other addresses attempting to post receive a non-customizable rejection message.
Send= Editor,Hold,Confirm Editor= editor-address(es)	Only address listed in the Editor= keyword can post to the list without moderation. Editors are required to confirm their own postings. Any non-editor address attempting to post to the list will receive the message defined by the POST_EDITOR template, and the message will be forwarded to the first editor listed (or Moderator= addresses, if defined). The editor or moderator(s) must be careful not to OK these or they will be distributed.
Send= Editor,Hold,Confirm Editor= editor-address(es) Default-Options= NOPOST	Same as above, except that subscribers that attempt to post will receive a non-customizable rejection message, and their post will not be forwarded to the editor or moderators. Non-subscriber posts will still be forwarded to the moderator, as above. If the editor addresses are subscribed, they must be set to “POST” before they will be allowed to post.

The following table contains some header keywords that you may want to consider setting in addition to those in the above table. Keywords appearing without a suggested value may have multiple settings and/or options to consider. For more information about assigning keyword values, see the List Keyword Reference document or the Keyword Wizard in the Web Interface.

Table 4-2 Other Keywords to Consider for an Announcement Style List

Keyword	Suggested Value
Auto-Delete=	Yes,Full-Auto (set Max, Delay, and Probe values as appropriate for you list)
Change-Log=	Yes
Confidential=
Default-Options=
Digest=	No
Notebook=
Reply-To=	Sender,Ignore
Subscription=	Open,Confirm
Validate	Yes,Confirm (Yes,Confirm is the minimum recommended protection. For stronger protection, see the List Keyword Reference document or the Keyword Wizard.

You may also want to customize the following templates. For more information on customizing template, see Section 6 Customizing Mail and Web Templates.

Table 4-3 Templates to Customize for an Announcement Style List

Welcome Message	ADD1	BOTTOM_BANNER
Farewell Message	DELETE1	BOTTOM_BANNER_HTML
$SIGNUP	INFO	TOP_BANNER
SIGNUP1	POST_EDITOR	TOP_BANNER_HTML
SIGNOFF2
You may also want to customize the following templates, unless you’ve disabled Auto-Delete or set Auto-Delete=Manual.
AUTODEL	PROBE1	PROBE2

4.2 Two-Way Discussion Lists

Two-way discussion lists allow for interaction between group members. These open forums facilitate ongoing discussions among members. They are most commonly used for internal communication within an organization or group of people. For instance, many universities use secure "class lists" for interaction among students and teachers or to conduct remote teaching.

Unlike a one-way list, a discussion list not only allows, but also encourages interaction between members who are part of the group. Every member can write to the list, and in doing so, all members will receive a copy of the message. In this way, discussions can take place and views can be exchanged among a large number of people. Two-way discussion lists can be public or private depending on the way the list is configured. Public lists allow anyone to join and participate. Open public discussion lists tend to be large with many messages being posted (high volume). They can take up a lot of server space and they can be open to spamming, spoofing, and flaming if there are no security measures in place.

Closed or private two-way discussion groups can also be large and high volume, depending on the topic of the list, or they can be medium sized or very small. Subscriptions are monitored and are often subject to approval by a list administrator. Subscribers communicate amongst themselves on a specific topic. Incidents of spamming and flaming are generally low because only subscribers can post to the list, and their subscription request has been reviewed. Set up a discussion list by using one of the following sets of keywords.

Table 4-4 Keywords for a Discussion Style List

Keyword and Suggest Value	Description
Send= Public	Anyone, even non-subscribers, can post to the list.
Send= Private	Only subscribed addresses may post to the list. Messages from an address that is not subscribed will be rejected, even if the person sending the message is subscribed under a different address.
Send= Editor,Hold Editor= email-address,(listname)	This is known as a “self-moderated list”. All list subscribers are editors, and therefore their posts are not moderated. Messages from non-subscribers, instead of being rejected as in a Send=Private list, are forwarded to the primary editor (or Moderator= addresses if any are defined) for approval.
Send= Public Default-Options= REVIEW Editor= email-address	For non-subscribers, this is similar to the previous setting, as the REVIEW default option applies to non-subscribers as well as new subscribers. Thus, messages from non-subscribers are forwarded to the primary editor (or Moderator= addresses if any are defined) for approval. All subscriptions are initially set to “REVIEW”, so that there may be a “probation period” for new subscribers. When a message comes from a subscriber that is set to “REVIEW”, it is forwarded to the primary editor (or Moderator= addresses if any are defined) for approval. When the probation period is over, the owner may set the individual subscription to “NOREVIEW” so that posts from that address are no longer “moderated”. This prevents spammers from signing on to a private or self-moderated list with open subscriptions, for the sole purpose of sending spam and immediately signing off. It also bypasses one of the problems of a self-moderated list, which is that individual posting limits are not enforced for list editors and therefore setting the second value of the Daily—Threshold= keyword is useless on a self-moderated list.

The following table contains some header keywords that you may want to consider setting in addition to those in the above table. Keywords appearing without a suggested value may have multiple settings and/or options to consider. For more information about assigning keyword values, see the List Keyword Reference document or the Keyword Wizard in the Web Interface.

Table 4-5 Other Keywords to Consider for a Discussion Style List

Keyword	Suggested Value
Attachments=
Auto-Delete=	Yes,Full-Auto (set Max, Delay, and Probe values as appropriate for you list)
Change-Log=	Yes
Confidential=
Daily-Threshold+
Default-Options=
Digest=
Moderator
Notebook=
Reply-To=
Sizelim=
Subscription=	Open,Confirm
Validate	Yes,Confirm (Yes,Confirm is the minimum recommended protection. For stronger protection see the List Keyword Reference document or the Keyword Wizard.

You may also want to customize the following templates. For more information on customizing template, see Section 6 Customizing Mail and Web Templates.

Table 4-6 Templates to Customize for a Discussion Style List

Welcome Message	SIGNOFF2	BOTTOM_BANNER
Farewell Message	ADD1	BOTTOM_BANNER_HTML
$SIGNUP	DELETE1	TOP_BANNER
SIGNUP1	INFO	TOP_BANNER_HTML
You may also want to customize the following templates, unless you’ve disabled Auto-Delete or set Auto-Delete=Manual.
AUTODEL1	PROBE1	PROBE2
If the list is self-moderated or is set to Default-Options=Review, then you may also want to customize the following templates.
POST_EDITOR
If you are implementing restrictions on posting contents, then you may also want to customize one or more of the following templates.
CONTENT_FILTER	BAD_CONTENT	BAD_ATTATCHMENT
SIZELIM_EXCEEDED

4.3 Moderated Lists

Similar to the two-way discussion list, a moderated list allows for the exchange of postings between subscribers and administrators, but an editor or moderator receives all incoming messages. The editor or moderator then decides to accept the message and post it to the list, or reject the message and not post it to the list. Lists can be set up with more than one moderator and they can take turns reviewing messages in a “round robin” fashion or all moderators can receive all messages.

Moderated lists can be of any size and subscriptions can be open or closed, depending on the type of list you want. Spamming and flaming are much less likely to happen on this type of list because all the postings are subject to approval by a person before they can be posted to the list.

Moderators receive and review postings sent to the list, and either approve them to be sent through the list or reject them to prevent them from being sent to the list. If there are multiple moderators, the list postings can be sent to each moderator in turn in a “round-robin” fashion or to all moderators. In the “round-robin” scenario, each message is sent to only one moderator for approval, sending one message to each moderator in the order listed in the list header before cycling back to the first moderator. The “round-robin” scenario allows a heavy load to be shared among several moderators. In the scenario where messages are all sent to all moderators, the first moderator to get to each message can approve or reject it. You would use this latter scenario if you want approvals to be made as soon as a moderator is available to review it.

The editors are those addresses that are allowed to send messages to the list without requiring moderation. The first address listed in the “Editor” keyword definition is known as the “primary” editor. If there is no “Moderator” defined, the primary editor is used as the sole moderator. The primary editor must always be an individual email address, but subsequent editors can be a list name enclosed in parentheses, meaning that all the subscribers on that list are allowed to post without being moderated. As a result, you can set up a separate list whose members are the editors of this one (and where subscriptions are closed). If you use the current list name, you have what is known as a “self-moderated” discussion list: subscribers can post without their messages being moderated, but posts from non-subscribers must be approved (see Section 4.2 Two-Way Discussion Lists). Set up a moderated list by using one of the following sets of keywords.