The task of keeping the mailing list of subscribers up-to-date becomes a bit difficult when the number of subscribe addresses grows beyond a few dozen, because people tend to change their e-mail addresses from time to time. On a mailing list for a thousand subscribers from all over the world, the maintainer of the list typically must spend a great deal of time editing the list file, removing or adding addresses. Most modern list servers allow people to perform these tasks themselves. List servers typically are able understands a number of commands on the subject line, like ``subscribe'' and ``unsubscribe''.

If you want to have your address added to a mailing list, you can send an e-mail to the mailing list address and put the command subscribe as the first word of the Subject: line. The mailing list daemon will then add your address to the list automatically (unless the list is a closed list); a message is then sent back to the sender of the message indicating that the subscription was successful. Similarly you can remove your address from a mailing list by sending the command unsubscribe in the Subject: line. Important Unlike many mailing list managers, there is no special account for processing subscribe and unsubscribe messages. Subscribe and unsubscribe requests are processed immediately. In addition to the sending mail to subscribe and unsubscribe, the Sambar Server can perform these actions via Web forms.

The type of mailing list described so far is known as a public mailing list. That is a list that is open to everyone to subscribe. Lists that are closed allow only certain people to subscribe. Public mailing lists are widely used on the Internet for discussion forums, while closed mailing lists are typically used by companies or organizations for maintaining internal forums, that are not meant for everybody. The Sambar Server Mailing list manager can maintain both kinds of lists, as well as variations of public and closed lists.