The important point for now is that some delivery agents deal with local delivery,
whereas others deal with delivery over a network.
1.6.8 Role in TCP/IP
The sendmail program has the internal ability to transport mail over only one kind of
network, one that uses TCP/IP; the following line instructs sendmail to do this:
Msmtp, P=[IPC], F=mDFMuX, S=EnvFromSMTP/HdrFromSMTP, R=EnvToSMTP/HdrFromSMTP,
The [IPC] might appear as [TCP], but note that, beginning with V8.10 sendmail, th e
expression [TCP] is deprecated, and it has been dropped entirely in V8.12.
When sendmail transports mail on a TCP/IP network, it first sends the envelopesender??™s
address to the other site. If the other site accepts the sender??™s address as
legal, the local sendmail then sends the list of envelope-recipient addresses. The other
site accepts or rejects eachrecipient address one by one. If any recipient addresses
are accepted, the local sendmail sends the message (header and body together). This
kind of transaction for sending email is called SMTP and is defined in RFC2821.
* Actually, delivery agent definitions often span multiple lines.
This is the Title of the Book, eMatter Edition
Copyright ?© 2007 O??™Reilly & Associates, Inc. All rights reserved.
1.6 Basic Roles of sendmail | 17
1.6.9 Role in UUCP
UUCP is an old-style means of moving email between machines that are only connected
with dial-up modems.
Pages:
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65