mail delivery on LAN - with Linux

[Shiraz Baig]

Sir,
  This is in continuation of previous discussion on
the subject.
  As mentioned earlier, I am trying to configure mail
on Linux LAN.  I shall use the names of two machines
"dtlaptop" and "unix11". The domain name is
"awt.com.pk".
First I installed sendmail on two machines, "dtlaptop"
and "unix11". 

I tried to send the mail from one to the other. It did
not go anywhere. It kept sitting on the sender's
machine. Giving a message after expiry time that mail
could not be delivered because of "relaying denied". I
tried a method of enclosing the address in square
brackets. But it still did not work.

Then I installed DNS on the machine "dtlaptop". I also
configured "dtlaptop" as mailserver with an MX entry
in the DNS records. On the "unix11", I gave the
address of "dtlaptop" as the name-server. 

I ran the "named" server. I found that now I could
send the mail from any user of one machine to any user
of the other machine.

I killed the "named" server, and I found that I could
not send the mail. I restarted the "named" server and
I could again send the mail. So, it appears that
/etc/hosts file is not sufficient. We have to install
the DNS to send the mail. Is my conclusion correct?

So far so good. But there is one problem. When I wish
to send mail from a user at one host to a user on the
other host, I have to mention the hostname.
For example, if I wish to send the mail from user1 on
"dtlaptop" to user2 on "unix11", I have to give the
recipient address as user1 at unix11.awt.com.pk
If I do not give the hostname, then my mail does not
go and keeps sitting at the sender machine.

So, the problem is why do I have to mention the
hostname in the address. Why can't I give the address
as 
          user1 at awt.com.pk
It should automatically locate the mail server and
deliver the mail there. (I have created all my users
on the mail server). I think, my problem can be solved
thru creating an alias. But then why do we need the
entry of "MX" in the DNS records. Then any host can
receive the mail. For example, in this case users at
unix11 are also receiving the mail. Or maybe I am
missing something.

I tried to check the DNS configuration thru "dig".
Here are the results of a query thru dig:
        $ dig any awt.com.pk


; <<>> DiG 9.2.1 <<>> any awt.com.pk
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id:
27595
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 3, AUTHORITY:
0, ADDITIONAL: 1

;; QUESTION SECTION:
;awt.com.pk.			IN	ANY

;; ANSWER SECTION:
awt.com.pk.		259200	IN	SOA	awt.com.pk.
hostmaster.awt.com.pk. 199802151 28800 7200 2419200
86400
awt.com.pk.		259200	IN	NS	dtlaptop.awt.com.pk.
awt.com.pk.		259200	IN	MX	10 dtlaptop.awt.com.pk.

;; ADDITIONAL SECTION:
dtlaptop.awt.com.pk.	259200	IN	A	192.168.1.249

;; Query time: 0 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Sat Jan  8 22:18:03 2005
;; MSG SIZE  rcvd: 130

Thanks, bye

    




		
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