LinuxSA Mailing list archives

  From: Jake Hawkes <jake@infinitylimited.net>
  To  : Steve Sloan <steve@lansol.com.au>
  Date: Fri, 28 Apr 2000 08:29:48 +0930

Re: Sendmail - slightly off topic

Steve Sloan wrote:
> 
> Hi
> 
> I have been asked to setup an e-mail server which I would like to use
> sendmail for but this site already has a web page hosted by Bigpond. My

Ok, then I assume you already have a domain name - eg
www.yourdomain.com.au

> question is how do I arrange for the email to point to this private server


given that you already have a domain name, there must exist somewhere
(probably on a big pond server) a DNS record for your domain. The DNS
record stores info about domain names and IP addresses.

In this DNS record is information about Mail eXchange (MX) records. So,
if your permanent link to big pond gave your an address of 10.1.1.1, and
a machine name of fred01.bigpond.com.au, then you would set up an MX
record like this:

		MX	10 fred01.bigpond.com.au.
		MX	20 backupmail.somewhere.com.au 

the second line is optional. without it, if fred01.bigpond.com.au is
down, the mail bounces (or is delayed and tried later)

somewhere in the bigpond DNS system, there will be an entry that looks
like this:
fred01.bigpond.com.au	IN	A	10.1.1.1 ; probably dynamically created


this way, when someone send mail to fred.nurk@yourdomain.com.au, the
sending mail server looks up the MX record for yourdomain.com.au finds
the lowest MX number (10) and contacts that host (fred01.bidpond.com.au)
on port 25, and talks to your sendmail program.

Then configuring sendmail is a HOWTO exercise :)

> ie. we want to use bigpond direct for the connection, so I guess I need to
> set up something like mail.domainname.com.au to point to this new server.

dont be fooled my machine names. e.g. "www" just so happens to be the
machine name people use for web pages. "mail" is another example of
this. When you send mail to fred@abc.com.au the mail server doesn't send
to the machine mail.abc.com.au, it looks up the MX records for the
domain abc.com.au.

if you look at the headers of this very email, you will see that it came
from my mail server called "zero", and I think you'll find it was
remailed by the machine "elizabeth" which is a netcraft mail server.

> On a similar line, is there anything I need to know about setting up more
> then one domain for sendmail on the one box or is this straight forward ?

There is a HOWTO that goes into alot of detail on this issue.

--
Jake Hawkes, B.Eng (CSE)

"I'm only smart enough to know how stupid I am", Joe Strummer.

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