Listserve

An electronic mailing list or email list is a special use of email that allows for widespread distribution of information to many Internet users. It is similar to a traditional mailing list – a list of names and addresses – as might be kept by an organization for sending publications to its members or customers, but typically refers to four things:

Electronic mailing lists usually are fully or partially automated through the use of special mailing list software and a reflector address set up on a server capable of receiving email. Incoming messages sent to the reflector address are processed by the software, and, depending on their content, are acted upon internally (in the case of messages containing commands directed at the software itself) or are distributed to all email addresses subscribed to the mailing list.

A web-based interface is often available to allow people to subscribe, unsubscribe, and change their preferences. However, mailing list servers existed long before the World Wide Web, so most also accept commands over email to a special email address. This allows subscribers (or those who want to be subscribers) to perform such tasks as subscribing and unsubscribing, temporarily halting the sending of messages to them, or changing available preferences - all via email. The common format for sending these commands is to send an email that contains simply, the command followed by the name of the electronic mailing list the command pertains to. Examples: subscribe anylist or subscribe anylist John Doe.

Electronic mailing list servers may be set to forward messages to subscribers of a particular mailing list either individually as they are received by the list server, or in digest form in which all messages received on a particular day by the list server are combined into one email that is sent once per day to subscribers. Some mailing lists allow individual subscribers to decide how they prefer to receive messages from the list server (individual or digest).

One type of electronic mailing list is an announcement list, which is used primarily as a one-way conduit of information and may only be "posted to" by selected people. This may also be referred to by the term newsletter. Newsletter and promotional emailing lists are employed in various sectors as parts of direct marketing campaigns.

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Wikipedia