Re: [exim4] mixed up about terminology
On 10/5/2014 11:16 PM, Harry Putnam wrote:
> Jerry Stuckle <jstuckle@attglobal.net> writes:
>
>> The first question - why do you think you need to relay to other
>> networks, even if they're your own? Do you have other SMTP servers
>> running on those networks?
>
> Good question and apparently thee is no reason. It stemmed from a deep
> seated confusion about what relaying means. All I really want is to
> be able to do this:
>
> On my lan machines:
>
> HOST-1
> HOST-2
> [...]
> HOST-mail-server now being configured
>
> HOST-[12...N] would have the server host above listed as smarthost in
> there respective mail config.
>
> So they would all be sending mail by way of server host.
>
> I guess that is not what is meant by relaying?
>
>
But would all of these other systems on your LAN have Exim or another
MTA (Mail Transport Agent) running?
You don't need an MTA on a system to send email. All you need is to be
able to access an MTA. The rest of the systems only need a MUA (Mail
User Agent), such as Icedove, Mutt or others.
In most cases, when you send an Email message, you will connect to your
MTA and send the message. That MTA will then connect to the recipient's
MTA and send the message, where the user can pick it up.
Relaying means there is one or more MTA's between the sender's and the
recipient's; that is the sender's MTA sends a message to a second MTA
which then relays it to the recipient's MTA.
Once again, I strongly urge you to read up on how email processing works
and Exim specifically. You can get the Exim manual at
http://www.exim.org/docs.html. The whole thing is rather long, but you
don't need most of it. However, you should at least read the first 3
chapters or so in their entirety and understand them. Then look through
the rest to familiarize yourself with what it says.
Those who think Exim is easy to configure for a secure system don't
understand it. I've been working with Exim for about 11 years and have
configured and maintain several systems in that time. I still don't
call myself an expert; in fact right now I'm trying to troubleshoot a
problem where a blacklist isn't working.
And while my first system wasn't an open relay, I've found other
potential holes in my configurations which I have since closed.
Debian's default configuration helps - but is not the last word.
Jerry
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