I have a Internal Mail server (Sendmail 8.x), The same server runs as Proxy (Squid),
The internet leased line is connected from the router to the Mail/Proxy server. Whenever the
internet goes down the endusers are NOT ABLE TO SEND AND RECEIVE THE INTERNAL MAILS.

The end users are using Outlook Express to send and receive the mails.

Even if the Internet is down, The clients should be able to send are receive
the internal mails.

Hi Arjun ,

It depends on your routing and DNS entries.

All your internal clients need to know that a.b.c.d is the ip address of your.domain.com ( ie;DNS entries should be in perfect order).
I guess u have windows clients, so check the lmhost file and make the necessary changes or you can simply configure a DNS server.
verify it by making ur clients ping the mail server with the name and not the IP address.

If what u mentioned in ur post is true than U better not face ur IT manager as it seems that u have been routing internal mails through the internet !!!!!!

Hope this clears up things for you.

Regards,
Vipul.

No ! The internal mails are NOT routed through internet. But still i dont understand why it searches for the net connection. I am working around the DNS.

Hi Arjun ,

Now wait a minute.... let me make it more simple for you.
Let us first get ur local network straight and in order.
I think ur too much messed up in the DNS thing!!! so let me clarify (as i have already told u in my personal mail) that ur local in house mails will work even without a DNS server !!!

ASSUMPTIONS:
Internal - Network IP : 192.168.1.X
Mail-server IP : 192.168.1.100
Mail suffix : mallik.com ex; my id will be xanthium@mallik.com

Do the following check up at your End .
1. First remove DNS entries from /etc/resolv.conf and /etc/nddswitch.conf files. So now basically ur dependent on
the /etc/host file for name resolution ( no DNS mess for you).
So now lets get ur system working without a DNS.

2. Now make changes in the /etc/host file to reflect ur mail suffix
so that if i do
nslookup -sil mallik.com

then u should get ur ip address ... if ur able to do so then ur half way through.

3. Retstart sendmail and check on what its listning by the command netstat -nl

if u dont see it listning on ur IP then edit the sendmail.cf file
and search for line that reads something like :

O DaemonPortOptions=Port=smtp,Addr=127.0.0.1, Name=MTA

please change it to


O DaemonPortOptions=Port=smtp,Addr=192.168.1.100, Name=MTA


4.Now for accepting mails for our domain edit the file
/etc/mail/local-host-names . Simply put the domain name, mallik.com, in the file. If u dont find that file then put it in the
/etc/sendmail.cw file.

5.Now lets get down to the relaying part. edit the file
/etc/mail/access

and put in ur local network ID in it as mentioned below :

192.168.1. RELAY


(NOTE the dot (.) after 168.1. <--- ... this ensures every one n ur local network only gets to relay mail through ur mail relay server)

Now from the command prompt issue the command

makemap hash /etc/mail/access.db < /etc/mail/access

In case u want to reject certain users from using ur mail servers then put in their IP address in the /etc/access file

192.168.1.28 REJECT
192.168.1.71 ERROR:"550 Contact M Arjun for acct"

and again issue the makemap comamnd mentioned above.


6. Now configure ur POP or Imap s/w as per ur needs.

Now ur probably wondering why i mentioned u all this ?
Well just to say that for local in house u can do without a DNS s/w such as BIND !!! just entries ur /etc/hosts file should suffice
just ping ur machine name and it should give u the result.


I hope this helps u .

Post again with ur result.

Regards,
Xanthium.

Hi ,

This is just few of things that i forgot in my previous mails.

Just ensure u have following entries

/etc/hosts - should have

192.168.1.100 mallik.com

in the file /etc/nsswitch.conf make changes so as to read :

hosts: files dns nisplus nis


Now once u have verified that internal mails are working fine u NEED to move on and have connection with external world so u should have a working DNS MX record for ur mail server so that external world can send mail to u and u can mail the as well !
Also make changes in ur /etc/resolv.conf and /etc/nsswitch.conf
to reflect the IP address of ur DNS server ... ie
/etc/resolv.conf should have entries

domain mallik.com
nameserver XXX.XXX.XXX.XXX

Use nameserver IP addresses specified by your ISP or if u have ur own DNS server then put ur own IP ... the IMP thing is the MX record. Check if ur able to ping external world.

Thats it.


Regards,
Xanthium.