A mailing list is a collection of names and addresses used by an individual or an organization to send material to multiple recipients. The term is often extended to include the people subscribed to such a list, so the group of subscribers is referred to as "the mailing list", or simply "the list".
Historically mailing lists preceded email/web forums; both can provide analogous functionalities. When used in that fashion, mailing lists are sometimes known as discussion lists or discussion forums. Discussion lists provide some advantages over typical web forums, so they are still used in various projects, notably Git and Debian. The advantages over web forums include the ability to work offline, the ability to sign/encrypt posts via GPG, and the ability to use an e-mail client's features, such as filters.[1]
Mailers want to know when items are delivered, partly to know how to staff call centers. Salting (or seeding) their lists enables them to compare delivery times, especially when time-of-year affects arrival delays.[2] It may also provide information about poor handling of samples.[3]
Having seeded entries in an eMail list simplifies tracking who may have "borrowed" the list without permission.[4]
When similar or identical material is sent out to all subscribers on a mailing list, it is often referred to as a mailshot or a blast. A list for such use can also be referred to as a distribution list.
Mailing lists are often rented or sold. If rented, the renter agrees to use the mailing list only at contractually agreed-upon times. The mailing list owner typically enforces this by "salting" (known as "seeding" in direct mail) the mailing list with fake addresses and creating new salts for each time the list is rented. Unscrupulous renters may attempt to bypass salts by renting several lists and merging them to find common, valid addresses.[5]