Need a help to configure exchange server

Hi all, any one help me out to configure the following scenario...

Just we installed SBS 2008 with exchange 2007. We created users with exchange mailbox in abc.local domain. Our abc.com is hosted by a third party service provider and it has four of our top management mailboxs. Now I need to configure the following things.

1. Mail boxes for internal communication only  ie., within abc.local domain

2. Mail boxes with external communication    ie., internal and external

3. Mail boxes already exists in our third party hosted domain should get both our internal and external mails.

 Also the users who are all having external communication should have the suffix  @abc.com  instead of @abc.local

Regards....Sridhar

To answer question:

1. On receive connector, there are Client and Default Connector. Client Connector is for internal Exchange user to communicate with each other while Default connector is to Exchange server. By default after you build your exchange enviroment which must include at least CA, Hub and Mailbox, the internal communication should working as fine.

2. To able your abc.local to communicate with external, you must configure "Sender Connector". You can found this at Organization level>Hub Transport. Normally, specify as * for any external MX records, which mean you can send any emails to external user. If you would like to external to able communicate with your internal user, then you must configure another "Receive Connector" at Server Level>Hub Transport.Create new Receive Connector as Outbound and select the "anonymous" at Permission tab.

3. For mailbox that already exist in third party. You may create a "Contact" on your exchange server 2007 and add the external email address and if you would like to send email to them, their "Contact" will appear in Global Address List or else, you can configure mailbox for them in your exchnage 2007 then confirgure mail forwarding to their third party email address.

4. You can create addtional email name space in user mailbox. Lauch the EMC>Open the user properties>Email Tab>and add the names@abc.com as primary address. If you have a lot of user who will conmunicate with external then you can create a "Transport Rules". Please check at Organization level>Hub transport.