Shit ! Sorry guys. There is a problem with the spam filter on my server. It's marking my outward emails as spam, not just inwards. In this case
it's because mtnl static ip is marked somewhere as a spam source.
Oops again. It's a mtnl dynamic ip
Any Internet facing mail server directly relays mails should have a Static I.P Address with a reverse PTR record set.
Many mail servers are configured to lookup RBLs that reject mails that originate from servers that do not have a reverse DNS record set. The reverse DNS lookup is essential for the recipient mail servers to correctly understand where the Mail originated from and the setting of reverse DNS records (PTR) record is now a standard practice followed by any server on the Internet directly relaying mails (this is mostly to prevent spam).
If you want to have your own Corporate Mail Server directly relay mails to the Internet, I highly recommend getting a static I.P Address from MTNL. The Static I.P Address from MTNL costs Rs 1000/- a year (for home use) and the Static I.P Address thus provided by MTNL also has a proper PTR record in place. You can also request MTNL to change this PTR record to something professional like mail.your-company name.com or something similar if you want to.
Another option you have is to use a smarthost to relay mails to the internet for you. A smart host is a dedicated Email server (mostly provided by your ISP or a third party) that has all the necessary settings in place for you to send your outgoing mails to it, and the relay host in turn will relay it to the Internet.
Please also refer to these URLs:-
http://en.wikipedia.org/wiki/Reverse_DNS_lookup http://en.wikipedia.org/wiki/Sender_Policy_Framework http://en.wikipedia.org/wiki/DNSBL
Regards,