لطفا منتظر باشید ...
Chapter 19.
Push Mail Protocol: SMTP
Mail Protocols: POP and IMAP, covered servers that dealt with part of the task
of mail delivery. POP, IMAP, and other pull mail protocols allow end users to
retrieve their e-mail from a central mail server system. There are two other
aspects of mail delivery, though: delivering the mail to the central mail
server, and sending outgoing mail. As it happens, both these tasks are handled
by push mail protocols, so called because the
sender initiates push mail transfers. The relationship between push and pull
mail protocols is covered in the "
the Simple Mail Transfer Protocol (SMTP). The
vast majority of the mail delivered on the Internet passes through at least one
SMTP transfer. Pull mail servers usually also run an SMTP push mail server so
that they can accept mail for local delivery as well as accept outgoing mail
from local systems, addressed to outside destinations. For this reason, SMTP
servers are extremely important for any Linux system that's to handle mail. Every
major Linux distribution ships with at least one SMTP server, but the default
server varies from one distribution to another. This chapter covers the three
most common Linux SMTP servers: sendmail, Exim, and Postfix. This chapter also
covers a tool that's frequently used in conjunction with an SMTP server to
process mail after it's been received by the server computer: Procmail. Before
delving into the details of SMTP server configuration, though, it's important
to understand when you should run such a server, which server is best to run,
and how to configure your domain to handle a mail server.Although many networks can make do with only
minor changes to mail server configurations from the default, other networks
require extremely complex mail server configurations. If you need more
information than can be presented in a single chapter, you may want to obtain a
book on your mail server of choice. Examples include Costales and Allman's Sendmail (O'Reilly, 1997), Hunt's Linux Sendmail Administration (Sybex, 2001), Hazel's Exim: The Mail Transfer Agent (O'Reilly, 2001),
Blum's Postfix (Sams, 2001), Sill's The qmail Handbook (APress, 2001), and McCarthy's The Procmail Companion (Addison Wesley, 2001).
