The following document was written by Florin Neumann, Department of Geology, University of Toronto, and originally appeared in CAP Newsletter 17(2):24-27, 1994.
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How do Internet Discussion Lists Work?
Each list has associated with it two e-mail addresses, the list address and the listserv
address. A message sent to the list address will be taken over by a special piece of software called the listserver and distributed to every subscriber to the list.
A message sent to the listserv address will be interpreted by the listserver as a command and will not be sent any further; if the listserver understands the command it will perform it and send the results to the originator of the message; if it doesn't, it will send back an error message, which usually also contains a help file with a synopsis of commands the listserver understands.
Say you want to join the list morus. The list address is email@example.com; the list-server address is firstname.lastname@example.org.To join morus you must send a command to the listserver to add your name and address to the list. Usually the command is an e-mail message with a blank subject line and containing the following line in the body of the message:
SUBSCRIBE MORUS YourName
If you send this message to email@example.com the listserver will not interpret it as a command at all; instead it will distribute the message to every subscriber! Result: rather than having your name added to morus, you will have generated a bit of bad feeling from busy subscribers who find a useless message in their mailbox.
But if the message is sent to the listserver address (firstname.lastname@example.org), the listserver will interpret it as a command; your name will be added to morus and you will receive a welcome message containing a short description of the list and its rules, and a synopsis of commands understood by the listserver. (It's a good idea to save this message for future reference.) Most listserver commands require that you specify the name of a list because one listserver usually services more than one list.
To cancel your subscription to morus you will have to send to the listserver address (NOT the list address) an e-mail message with a blank subject line and containing the following line in the body of the message:
and the listserver will reply with a good-bye message.
The most common mistake is to send a subscribe/unsubscribe command to the list address, rather than the listserv address. There is really no good excuse for this carelessness (especially for the unsubscribe command).
Solution: Send the unsubscribe (or signoff) command to the listserv address, rather
than to the list address. All the details should be in the welcome message which (of course) you have saved for future reference! If it doesn't work, or if you can't find it, send a message to the list owner/moderator (not to the list).
Some e-mail programmes (Pegasus Mail in particular) are configured to include automatically in the e-mail message a confirmation request. When a message containing such a request is browsed with a compatible mailer, the programme will automatically send back to the message's originator an rcpt (an e-mail message confirming the receipt of the initial message). That's all fine and dandy, but if there is a list between the sender and the browser, then the rcpt will be sent back to the list, i.e.,
to each and every subscriber! It's not a pleasant sight to check your mail one morning and find your mailbox clogged up with 30 rcpt messages.
Solution: Make sure that (a) your mailer's confirmation request feature is disabled, and (b) your mailer's automatic response to confirmation requests is disabled.
If you change your e-mail address the listserver will regard you as a different person. It won't accept a command to cancel the old subscription issued from the new address. Postings will continue to be sent to the old address, and if the old address has become invalid, they will be bounced back to the list, i.e., to every subscriber to the list.
Solution: If you are going to change your e-mail address, cancel your subscription and
re-subscribe to the list from the new address. If you haven't been able to do that, as a last resort, contact asap the list owner/moderator and ask him to remove your old address from the list.
If you have joined several lists, you may easily find everyday over 100 messages waiting in your mailbox. You can decrease this number by using the digest option, which means that new messages posted to the list are not sent to you as they arrive, but are accumulated into digests that are mailed to you periodically. The digest option is highly recommended because it also reduces net traffic and overhead and resource utilization on the machine which runs the listserver.
To set your mail to digest, send a message (no subject) to the listserv address (not the list address!) containing only the following line:
SET xxxx MAIL DIGEST
(Substitute the string xxxx with the list name).
Note that not all lists support the digest option (e.g., PaleoNet, Quaternary, and Rocks-and-Fossils).
If you are going to be away from your computer for a week or more your mailbox may fill
up with unread messages. Usually the system manager has set an automatic limit for the number of unread messages a user mailbox may hold; if the limit has been reached, incoming messages are bounced back to the list. To prevent this, send a message (no subject) to the listserv address (not the list address!) containing only the following line:
SET xxxx MAIL POSTPONE
(Substitute the string xxxx with the list name.)
The listserver will stop sending you postings of digests until you reset it (e.g., by sending again the digest command).
You want to send a personal message to a colleague subscribed to a list but you don't
know his e-mail address. How can you get it? Well, you can ask the listserver. Just send a message (no subject) to the listserv address (not the list address!) containing only the following line:
(Substitute the string xxxx with the list name.)
The listserver will mail you back a file with a general description of the list (if the listowner/ moderator has been thoughtful enough to provide one), the list statistics, and a listing of all list subscribers with their e-mail addresses.
(Note that the listing produced by the review command will not include concealed addresses. To find out how to conceal your own address, send help to the listserver.)
Common sense and courtesy obtain in electronic communication just as they do in written or oral communication.
If you use the reply function to answer list posting, your reply will be sent to the list, i.e., to every subscriber. If your message regards only one subscriber, send your message directly to him.
Mailers can be configured to append automatically to an outgoing message a file, usually called .sig (for signature), containing your name, address, affiliation, etc. Try to keep the .sig file as small as possible: four to five lines is usually considered adequate.
E-mail makes it easy to include in your own posting a previous posting to which you reply. But do try to edit the quoted text as much as possible: eliminate the header and the signature and anything else which is not directly relevant to the point. Follow the usenet rule (your message should contain no more than 49% quoted text).
Send an e-mail message to email@example.com with a blank subject line and the following text:
//dblook job echo=no
database search dd=rules
//rules dd *
select xxxxx in lists
select xxxxx in intgroup
select xxxxx in new-list
This will look for all lists that have the string xxxxx in the list name, interest group description, or in the list of new lists. Substitute xxxxx with whatever it is you're looking for. You'll receive in a couple of minutes an e-mail message with the results of your search.
(Derived and modified from TidBITS #254, an online newsletter)
"Internet mailing lists are often hard to find, since there are so many. However, the LISTSERV home page supposedly lists all of them. It enables you to sort alphabetically or by category, and when you sort by category, you can get more detailed information on the list. The site appears to be a functional advertisement for a $99 tool (currently only dos-based, but a Mac version is in the works and slated for November  release) called InfoMagnet, which lets you find, search, and participate in listserv-based mailing lists. From the sounds of it, Info-Magnet is a front-end interface to the often-complex listserv commands."
"In addition, the E-mail Discussion Groups page enables you to search a database (maintained by Dartmouth College) of almost 6,000 mailing lists.The database is updated weekly."
Article written by Florin Neumann, Department of Geology, University of Toronto