Exim trouble

["Rajkumar S." <voidmain@myrealbox.com>]

Hi all,

I have a neatly configured exim running, but having problem with sending
mail to gnu.org.in. The problem is that the MX record is having an ip
address instead of name

Non-authoritative answer:
gnu.org.in      preference = 10, mail exchanger = 202.88.232.42

and the Exim complaints that

it appears that the DNS operator for this domain has installed an invalid
MX record with an IP address instead of a domain name on the right hand
side

What could be done to solve this. Why is exim refuses to accept an ip as
mx record.

raj