If your friend (the recipient) is in the same
neighborhood (on the same machine), only a single post office (sendmail running
locally) is involved. If your friend is in a distant location, the mail message will be
forwarded from the local post office (sendmail running locally) to a distant one (sendmail
running remotely) for delivery. Although sendmail is similar to a post office in
many ways, it is superior in others:
??? Delivery typically takes seconds rather than days.
??? Address changes (forwarding) take effect immediately, and mail can be forwarded
anywhere in the world.
This is the Title of the Book, eMatter Edition
Copyright ?© 2007 O??™Reilly & Associates, Inc. All rights reserved.
2 | Chapter 1: Some Basics
??? Host addresses are looked up dynamically. Therefore, machines can be moved
or renamed and email delivery will still succeed.
??? Mail can be delivered through programs that access other networks (such as
Unix to Unix Communication Protocol [UUCP] and Bitnet). This would be like
the post office using United Parcel Service to deliver an overnight letter.
This analogy between a post office and sendmail will break down as we explore sendmail
in more detail. But the analogy serves a role in this introductory material, so we
will continue to use it to illuminate a few of sendmail??™s more obscure points.
1.
Pages:
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40