How to enable internal domain mailbox enabled users to send/receive msgs to/from external domains i.e. yahoo.com, yahoo.fr, hotmail.com etc.

Hi friends...

I have one server running Windows Server 2003 Enterprise Edition. It is my DNS and DC. My DC name is XXX.ac.in

I have installed Exchange Server 2003 Enterprise Edition on the same machine. (Just for testing, then I will move it to another machine)

I have configured it and now internal users can send and receive mails by using MS-Outlook 2003, OWA (internally) and Outlook Express.

I want to know&

How can I expose my Exchange Server 2003, so that outside users (who have their account on other domains i.e. from Yahoo.com, Yahoo.fr, hotmail.com etc.) can send and receive email messages from my domain ? (XXX.ac.in)

I have not created any ROUTING GROUP...and I know that I need to create an SMTP CONNECTO, but how to do it and what else configuration I will need to enable my domain users to send/receive emails to/from outside domains.

There is a default SMTP Virtual Server installed with Exchange installation, so do I need to create another SMTP Virtual Server ?

I will publish my Exchange server on ISA 2004 later.

Please help me in this regard...

Hemant