[669] in RedHat Linux List
Re: Sendmail Question
daemon@ATHENA.MIT.EDU (Ian Burrell)
Thu Oct 24 00:01:32 1996
To: redhat-list@redhat.com
Date: Wed, 23 Oct 1996 20:59:14 -0700 (PDT)
In-Reply-To: <Pine.LNX.3.91.961024092945.1557E-100000@numedics.transport.com> from "Allen Francom" at Oct 24, 96 09:37:16 am
From: Ian Burrell <iburrell@leland.Stanford.EDU>
Reply-To: iburrell@leland.Stanford.EDU
Resent-From: redhat-list@redhat.com
>
> There's prorams that "run in the background" on Linux. Relative to mail,
> we have SENDMAIL, SMTP, POP2, POP3, and UUCP.
>
First, sendmail is a program, and SMTP, POP2, POP3, IMAP, and UUCP are
all protocols that various programs use.
> Sendmail is a router, nothing more.
>
It usually called a Mail Transfer Agent (MTA) and it transfers mail
between hosts and servers (computers that always connected to the
net). There are other MTAs, but sendmail is the most widespread one.
There are many MUAs, programs that people use to read their mail.
> SMTP is a "forwarding agent" - Is that a good description ?
> Simple Mail Transport Protocol
SMTP is the protocol that sendmail (and other MTAs) use to transfer
mail between machines.
>
> POP is Post Office Protocol.
>
This is used by many clients to download their mail. Most of this is
done directly by MUAs, although sometimes programs will feed the
downloaded mail into sendmail for local delivery.
> To make some analogies, sendmail is like the guy in the back room of the
> post office, sorting mail into this bin or that bin. SMTP is like the
> mail man, he picks up mail from the post office and delivers it to other
> mail-men, or other post-offices, he also can pick it up from the mail box
> and bring it back to the post office. POP is like a P.O. Box, you have to
> go to it to get your mail.
>
Good analogy. SMTP can also deliver directly to your home or office,
if you are running sendmail, a server that is always waiting to accept
mail.
- Ian
--
-- Ian Burrell == iburrell@leland.stanford.edu **
<URL:http://www-leland.stanford.edu/~iburrell/>
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