SENDMAIL not sending mails to other domains like GMAIL and REDIFF

#! /bin/ksh

SUBJ="Send mail from Unix "
FROM=test1@rediffmail.com
TO=test2@abc.com
CC=test3@gmail.com
ATT=STMT.DOC
(
cat << !
FROM : $FROM
To : ${TO}
Subject : ${SUBJ}
Cc : ${CC}
!

cat << !
HOPE THIS WORKS Test123
This sample E-mail message with the Unix sendmail utility.
!

uuencode ${ATT} ${ATT}
!

) | /usr/lib/sendmail -v ${TO} ${CC}
~

After running this script , mails are sending successfully to test@abc.com .
It is not sending mails to other domains GMAIL and REDIFF.    ABC.com is my home domain..


Please clarify , is there any setup has to be done ?Start Free Trial