[X-Unix] Beginners questions on Unix Mail

[Eric F Crist]

On Dec 20, 2004, at 7:22 AM, kim wrote:

> I am a complete beginner in Unix and I am trying to understand how to 
> send and receive email.
>
> First off, where does the Hostname come from? By that I mean, how is 
> it generated? Mine begins with the IP address, is followed by a bit I 
> don't understand, and ends with the domain name of the Internet 
> Service Provider.
>
> The start and end make sense to me, but where does that middle bit 
> come from? Does it mean anything in particular? And can I change it?

You've got a couple questions here, and neither has a very simple 
answer.  Let's start with a domain name.

Usually, with broadband internet providers, your machine name will be 
set to something like:

c-66-41-157-209.mn.client2.attbi.com

This is broken up into a few parts. The first part is my machine name, 
c-66-41-157-209.  Now, knowing people that work locally for my 
broadband provider, I know that this is my IP address, prefixed by the 
'c.'  The 'c' for attbi.com means this is a cable IP address.

The second part is '.mn.' I live in Minnesota, USA.  Third part is 
higher-level AT&T node information.  Lastly, you have the TLD, or 
Top-Level Domain name.  There are actually two schools of thought on 
TLDs.  Some folks consider the .com part the TLD, many others, 
including myself, consider the first part to the left the TLD.

On to the email!  You can easily create your own email server, with the 
very system you have running now.  I assume you're using Mac OS X.  
Whether it's the server edition or not, you actually have the full 
ability to run a mail, web, or other kinds of server, though some work 
will be necessary to do so.  Now, because you're able to run a mail 
server, doesn't mean you should.

An email server needs to be online 100% of the time.  There is 
generally a 4 hour window in which mail servers will try to connect in 
the event a server does go offline.

Many broadband providers specifically state in the EULA that you're not 
allowed to run a server.  If you want to run a mail server, there are 
plenty of tutorials out there on how to do so, whether you have a 
static IP address, or not.

One good place to read about how to setup an email server is 
http://sial.org/howto/sendmail/macosx/8.12.2-jaguar/  Note, the link 
may have wrapped.

HTH
_______________________________________________________
Eric F Crist                  "I am so smart, S.M.R.T!"
Secure Computing Networks              -Homer J Simpson
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