 | | | sendmail configuration on redhat | sendmail configuration on redhat 2003-01-17 - By Jason Dale
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Thanks for the input. With my sendmail setup , both relaying and listening
on the network device other than the loopback were disabled by default. I
had
to specifically enable those services. That's what the documentation told me
anyway. There were no DNS issues involved at all ; a traceroute to
"mail.somedomain.com" showed me that the MX record on our DNS servers
were pointing to the right IP address. That's where the sendmail.mc and
/etc/access* files became necessary for me.
As for the questions that I "think" I am asking , I realize that I am
probably not good enough to ask questions in the format required by
super-intelligent Linux list subscribers. What a pleasure life would
be if we could rid the world of neuron-depleted and academically
challenged bio-entities like myself , who didn't qualify for a MENSA
membership. The very best I can do is to try to 'visualize' how all the
pieces of this Linux puzzle fit together , ask my questions as best I
can , and hope that I don't get too much of a heated response.
-- -- Original Message -- --
From: "David Freeman" <dfreeman@(protected)>
To: <seawolf-list@(protected)>
Sent: Friday, January 17, 2003 2:41 PM
Subject: RE: sendmail configuration on redhat
>
> > For my own clarification , is there a difference between
> > Handling POP3 and SMTP requests , and actually BEING a POP3 / SMTP
> server ?
>
> I guess that depends on what question you think you're asking.
>
> SMTP = simple mail transfer protocol (from memory, it's a while since I
> actually checked that - could be simple mail transport protocol).
>
> An SMTP server runs on port 25 and handles sending of email as well as
> receiving email from clients to be delivered (either locally or to some
> SMTP server on the net somewhere).
>
> POP3 = post office protocol
>
> A POP3 server runs on port 110 and handles incoming requests for mail
> delivery from a client program.
>
> As both protocols work on different ports they quite happily co-exist on
> a single machine. It's no different to running a web server and DNS
> server on the same computer. The only thing you can't really do is run
> two daemons that want to use the same port and IP address combination.
>
> That said, on Redhat systems, the SMTP daemon is usually sendmail. This
> is NOT a POP3 server. You will also find a POP3 daemon - the newer
> releases are incorporated into the IMAP rpm from memory.
>
> As for the question, if you're "handling" POP3/SMTP requests then you're
> most likely operating POP3/SMTP daemons. You could, however, be
> proxying such requests which could be said to be "handling" without
> being a "server" depending on your definition of those terms.
>
> Every RH release I've used (seriously from about RH5, earlier as a hobby
> thing and I don't really recall for those earlier releases) is readily
> capable of acting as a mail server (both POP3 and SMTP) with no real
> requirement for altering sendmail.cf although before relaying and the
> like became common it used to be necessary to generate your own
> sendmail.cf if you wanted that sort of functionality. Most recent
> releases have had this capability ready to run.
>
> Perhaps if the person having problems cannot get mail serving working it
> could be related to DNS and, particularly, MX records rather than
> configuration of the daemons themselves.
>
> > If sendmail is
> > not
> > a POP server , how does it handle the incoming mail ?
>
> Incoming mail is the job of a mail transport agent, or MTA (a program
> that moves mail between servers). The usual protocol is SMTP and this
> is what sendmail does.
>
> Delivery of mail to a client (Outlook Express et al) is the job of a
> mail delivery agent, or MDA (a program that waits for client connections
> and sends locally stored email to that client). The usual protocol is
> POP3, although IMAP is also now popular, and this job is handled by a
> POP3 daemon (these days part of the IMAP rpm).
>
> CYA, Dave
>
>
>
>
>
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