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1.1 root 1: Here it is, on the fly.....
2:
3: SENDMAIL -- An Internetwork Mail Router
4:
5: Routing mail through a heterogenous internet presents many new
6: problems. Among the worst of these is that of address mapping.
7: Historically, this has been handled on an ad hoc basis. However,
8: this approach has become unmanageable as internets grow.
9:
10: Sendmail acts a unified "post office" to which all mail can be
11: submitted. Address interpretation is controlled by a production
12: system, which can parse both domain-based addressing and old-style
13: ad hoc addresses. Mail is then dispatched to an outgoing mailer.
14: This system can expand trivially. The production system is powerful
15: enough to rewrite addresses in the message header to conform to the
16: standards of a number of common target networks, including old
17: (NCP/RFC733) Arpanet, new (TCP/RFC822) Arpanet, UUCP, and Phonenet.
18: Sendmail is not intended to perform user interface functions or
19: final delivery. Sendmail also implements an SMTP server, message
20: queueing, and aliasing.
21:
22: This is approach is unique in that it allows external compatibility
23: with the old practices, and tries to make the mail system conform to
24: the user instead of the other way around. Although sendmail is not
25: intended to circumvent new standards, it is intended to make the
26: transition less painful. Sendmail does require certain base-level
27: standards on target mailers such as the basic semantics of certain
28: headers and the surface syntax of messages. New mailers can be added
29: trivially; for example, a Purduenet channel was brought up in twenty
30: minutes.
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