Overview

Every mail message has a set of destinations, called recipients or recipient addresses. At some point during the processing, handling, and forwarding of each recipient's copy of a message, the message will undergo final or local delivery. This cannot happen until the message reaches the host where the recipient actually reads her mail; one of sendmail.cf's principle functions is the recognition of local recipients and the local delivery of mail to them. If a recipient address is not found to be local, Sendmail sends it out via some network ("nonlocal") mailer in its role as a gateway or relay. This chapter describes local delivery.

Often a user will be known by some set of names other than (or in addition to) her login name. Sendmail's aliases database is a way to funnel mail from all of these names into a single mailbox. Likewise, a user will probably read her mail on some particular host, but it is inconvenient for other users to have to know which host that is, since a user might move her mailbox to a different host, or the host's name might be difficult to spell or to remember. The aliases database can direct a user's mail toward her mail host no matter which host in the local domain first receives any given message. This is particularly useful because it allows a user to appear to be reachable at the border gateway or on the...