Blame Documentation/Manuals/Docbook/Tcpi-ug/Services/Mail/overview.docbook

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<sect1 id="services-mail-overview">
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    <title>Overview</title>
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    <para>
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        The mail service provides the software required to let you
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        send/receive mail messages to/from others. The mail service is
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        supported by three basic components: the Mail Transfer Agent
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        (MTA), the Mail Delivery Agent (MDA) and the Mail User Agent
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        (MUA). The MTA is the program your mail client sends mail
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        messages to. The MDA, on the other hand, is the program your
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        mail client reads mail message from (i.e., this is the program
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        that lets you access your mailbox).  The saslauthd daemon is
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        used by the MDA to authenticate user's credentials (e.g., the
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        information required to grant access to an specific mailbox)
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        and in some cases by the MTA to authenticate users before
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        sending mail to it.  The MTA will listen on all network
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        interfaces it is attached to and will receive mail sent to
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        specific users inside specific domain names.
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    </para>
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    <para>
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        Inside &TC;; there is support for different MTAs (e.g.,
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        Sendmail, Postfix and Exim).  By default, the
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        <application>Sendmail</application> program is used as mail
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        transfer agent, however, we want to use Postfix for our
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        configuration. This way, to use Postfix as default mail
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        transfer agent and not Sendmail, it is required to use the
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        <command>alternatives</command> command.  This command will
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        present you a menu to chose between available mail transfer
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        agents installed in the system, so you can choose Posfix as
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        default option. Now that you've made Postfix the default mail
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        transfer agent, you can saftly remove the sendmail package to
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        avoid unused software to remain inside the computer.
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    </para>
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    <para>
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        Inside &TC;; there is support for different MDA (e.g., Cyrus
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        IMPA and Dovecot). By default, the Dovecot program is used as
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        mail delivery agent (which doesn't require any intermediate
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        daemon for athentication), however, we want to use Cyrus IMAP
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        for our configuration (which does require an intermediate
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        daemon called saslauthd for authentication).
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    </para>
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    <para>
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        Inside &TC;; there is support for different MUA (e.g.,
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        Evolution, Thunderbird and Mutt). By default, the Evolution
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        program is used and we stay with it :).
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    </para>
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    <para>
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        In this chapter we describe how to configure each one of these
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        components to let you send/receive e-mails to/from your
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        friends.
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    </para>
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</sect1>