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Module 05

Mail Transfer Agent (MTA) Basics

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Objectives

SendmailPostfixQmailExim

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Overview

SendmailSendmail was one of the first MTAs used on Unix

systemsThat fact, combined with the history of security

vulnerabilities that have plagued sendmail over the years, has caused its popularity to decrease over the last decade

Although most major Linux distributions provide a package for sendmail, none of them currently ship with sendmail as the default MTA.

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Overview

PostfixPostfix was originally designed in the late 1990s as a

more secure alternative to sendmailAt the time of this writing, postfix is currently very

popular in the Linux world, and is the default MTA shipped with the most popular Linux distributions.

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Overview

QmailQmail was developed in the mid 1990s to be as secure

as a mail transfer agent can beQmail is small, efficient, and secure, making it a popular

choice for resource-strapped systems.However, qmail has not been actively developed since

1997, and its lack of support for modern options such as IPv6 has limited its usefulness.

It is not commonly seen on newer Linux distributions

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Overview

EximExim is another example of an MTA that was developed

in direct response to the security issues with sendmail.

it is essentially a drop-in replacement for sendmail It is designed to be a general-purpose mailer for Unix-

like systems, and is widely used in relatively high volume environments

It was originally written in 1995 and still enjoys active development to this day.

Exim is currently the default MTA for the Debian GNU/Linux distribution.