A mailbox is identified by an email address. However, not all email addresses correspond to a storage facility. The term pseudo-mailbox is sometimes used to refer to an address that does not correspond to a definitive mail store. Email forwarding may be applied to reach end recipients from such addresses. Electronic mailing lists and email aliases are typical examples.
Access to a mailbox is controlled by a mailbox provider. Usually, anyone can send messages to a mailbox while only authenticated users can read or delete from their own mailboxes. An email client retrieves messages from one or more mailboxes. The database (file, directory, storage system) in which the client stores the messages is called the local mailbox.