Re: email servers

[Ron Johnson <ron.l.johnson@cox.net>]

On Thu, 2006-03-30 at 14:01 -0700, ChadDavis wrote:
> Hello.
> 
> I'm pretty unfamiliar with email servers.  I need to install a 
> server in my local network to use for development of another 
> application.  I just need a mail server available for the appli-
> cation.  I read some of the online documentation and became a 
> bit confused about what constitutes a server.   Postfix is on 
> the system.  What does it do?  I don't think it has anything to
> do with my email client, correct?  My email client talks to my 
> ISP's POP server for incoming mail, and my ISP's SMTP server for
> outgoing mail.  It seems like what I need is a SMTP server locally.
> 
> Is the postfix such a thing?  If not, what is an easy one to 
> install.


The MTA (Mail Transport Agent) move mail around from place to 
place.  Examples are:
    Sendmail
    qmail
    postfix
    exim
    Exchange Server

MUA (Mail User Agent) is the client.  Examples are:
    Netscape Mail
    Thunderbird
    Outlook (Express)/Exchange
    Evolution

POP (Post Office Protocol) does exactly that.  It emulates 
Post Office Boxes: just as the postal employee puts mail in 
your PO Box, where it waits until you pick it up, so the MTA 
puts mail in your "box" where it waits until your MUA fetches
it.

IMAP (Internet Mail Access Protocol) is a server-side alternative
to storing emails on your PC.  You read the email using an MUA,
but the email stays on the server.  Best for companies and tra-
velers.  Examples are:
    cyrus-imap
    courier-imap
    dovecot-imap
    uw-imap
    Exchange Server

So, if you want to send emails from box to box (and, of course, 
internally) on your LAN, install an MTA on each machine.  They
will have to be configured so that LAN traffic stays on the LAN
and internet mail is sent to your ISP's smtp server.

I recommend fetchmail (a remote mail retrieval and forwarding util-
ity) to get users' POP mail from the ISP and give it to your MTA,
which then gives it to your IMAP server.  Thus, all mail stays on
one box, making Sarbanes-Oxley, your Auditors and your users (when
they yell "Find that critical email I blithely deleted last week!!"
very happy.

-- 
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Ron Johnson, Jr.
Jefferson, LA USA

"A man can't be too careful in the choice of his enemies."
Oscar Wilde