We have implemented a Linux Mail Server and Internet Gateway using PCQuest 2005 (Fedora Core 3). Here we are using Postfix instead of Sendmail. And for downloading mail from our Internet Mail Server we are using fetchmail. For Internet we have a BSNL's Broadband Connection with Dynamic IP. Here every thing is functioning perfectly. In outlook POP3 and SMTP is Linux Server's IP 192.168.1.2.

Problem is ;
When we used to send a mail through outlook to Rediffmail / Sancharnet they are simply bouncing back to sender (outlook user) giving the below reply.
--------------------------
This is the Postfix program at host intranet.cysd.org.

I'm sorry to have to inform you that your message could not be
be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to <postmaster>

If you do so, please include this problem report. You can
delete your own text from the attached returned message.

The Postfix program

<abc@sancharnet.in>: host ndl1mx1-a-fixed.sancharnet.in[61.0.0.46] said:
550 5.7.1 No Reverse DNS Entry for host: 59.93.129.208 - authoritative host
not found (in reply to MAIL FROM command)

<abc6287@rediffmail.com>: host mail3.rediffmail.com[203.199.83.132] said:
553 Message from 59.93.129.208 rejected - see
a url (in reply to RCPT TO command)
---------------------

Similarly when we are sending the same to yahoo, it is receiving the mail but it kept in the BULK folder.

But, when we are sending the same to hotmail/ gmail they are receiving the mail and putting them into their INBOXs respectively.


What may be the problem in the setting of POSTFIX.

Thanks.