sendmail.mc:

MASQUERADE_AS(`pancard.utiisl.co.in')dnl   
MASQUERADE_DOMAIN(pancard.utiisl.co.in)dnl 

make -C /etc/mail

Comment this line : 
#O DaemonPortOptions=Port=smtp,Addr=127.0.0.1, Name=MTA      

On Primary Server
named.isl:

$TTL    86400
@       IN      SOA     islbom1.utiisl.co.in.   root.islbom1.utiisl.co.in.
                        (
                        2003080601      ;       serial
                        300     ;       Refresh
                        60      ;       Retry
                        1209600 ;       expire
                        43200)  ;       Minimum
                NS      islbom1.utiisl.co.in.
                NS      islbom2.utiisl.co.in.
                MX      10      islbom1
pancard         MX      10      islbom2
localhost       A       127.0.0.1
islbom1         A       203.94.228.20
islbom2         A       203.94.228.18
www     IN      CNAME   islbom1.utiisl.co.in.
www.pancard     IN      CNAME   islbom2.utiisl.co.in. 



named.isl.rev:
$TTL    86400
@       IN      SOA     islbom1.utiisl.co.in.   root.islbom1.utiisl.co.in.
(
                        2003080601      ;       serial
                        300     ;       Refresh
                        60      ;       Retry
                        1209600 ;       expire
                        43200)  ;       Minimum
        IN      NS      islbom1.utiisl.co.in.
        IN      NS      islbom2.utiisl.co.in.
20      IN      PTR     islbom1.utiisl.co.in.
18      IN      PTR     islbom2.utiisl.co.in.