Hello:
Question, if I add 2 more client pcs to my network (Joe and Sam). Would I need to put Joe and Sam into "A" records below with their IP addresses into the zone files in addition to setting up their accounts in the Mail Server Machine running Exim4?

Or will Joe and Sam on separate machines be able to send mail internally in this network to each other because they will have mail accounts setup on the Exim4 Server Machine.?



Here's my setup for DNS...:

The named.conf file...:
zone "example.com" {
type master;
file "/etc/bind/myzones/db.example.com";
};

zone "0.168.192.in-addr.arpa" {
type master;
notify no;
file "/etc/bind/myzones/db.192b";
};
======================

The Zone File...:
;
; BIND data file for local loopback interface
;
$TTL 604800
@ IN SOA ns.example.com. root.example.com. (
7 ; Serial
604800 ; Refresh
86400 ; Retry
2419200 ; Expire
604800 ) ; Negative Cache TTL
;
@ IN NS ns.example.com.
@ IN A 192.168.0.11
ns IN A 192.168.0.11

mail IN A 192.168.0.13

MX 10 mail.example.com.


==========================

The Reverse Zone File...:
;
; BIND reverse data file for local loopback interface
;
$TTL 604800
@ IN SOA ns.example.com. root.example.com. (
7 ; Serial
604800 ; Refresh
86400 ; Retry
2419200 ; Expire
604800 ) ; Negative Cache TTL
;
@ IN NS ns.
11 IN PTR ns.example.com.
12 IN PTR mail.example.com.

Each client will need an ip address and depending on your setup they may require dns or may not. Personally I think it's a good idea to setup dns, but it isn't necessary in all cases.

Hey Thanks. So I make sure I understand correctly, each client will need to be added to the 2 zone files in order for the exim4 Mail Server to receive the email for each client?

Zone..:
Joe IN A 192.168.0.14
Sam IN A 192.168.0.15

Rev zone file...:
14 IN PTR Joe.example.com.
15 IN PTR Sam.example.com.

Seems that using DNS for email involves alot more than for a webserver.
Like if I want to see www.example.com website in my network, the individual clients don't need to be added as "A" records in the zone files in order to access the website example.com. They just pull up www.example.com in their browser and they can see it because the DSN servers it up for them.

But it seems DNS needs the individual clients (lets say 20 or more client pcs if there were that many) to be added to the zone files. In addition to setting userId's up for the Exim4 server.

I was wondering if this is just the way it is with DNS setups when it comes to using an Email Server with it.

Is it possible to use NIS somewhere in this process. Perhaps DNS server can see the NIS maps. But I guess NIS needs to know the IPs of the individual clients as well. Just curious :-/

It is not required to have A record in DNS if your clients need to send mails. You only need to make entry of your mail server as MX record. Your clients only need to do is to update their /etc/resolv.conf entry with the DNS holding MX (mail server) record.

Thanks,
Deepak

It largely depends on how your server is setup, if your server rejects mail from hosts without a valid dns entry then yes you need to setup dns. If it doesn't then you don't necessarily need to setup dns although I think there are still benefits for doing so outside of a mail context and often inside it too

Ok thanks guys. Figured out that the Entries only needed to be added to my exim4 mail server. The "A" entries in the DNS zone files were not needed for each client PC. Like you mentioned above, I just configured my MUA (Evolution) to send and receive email.

Seems like my ISP are blocking any emails coming out of my exim4 Mail Server. They want everything to go through their smtp.blablah server. Bunch of baloney. They claim you have to sign up for their business account in order to send emails from your own email server. Bunch of crooks if you ask me, just another "Big Brother".