When you first deploy an appliance (physical or virtual) you will be taken through a setup wizard process. This is purely for inbound mail, so you will be required to supply the domain name you wish to allow mail to be accepted for and the IP address or hostname of your internal mail server.
At this point you should be able to direct mail through the system and it will both accept and deliver these messages to the correct location.
In the case of your second question, there may be a couple of ways of achieving this.
One would be to add gmail.com, yahoo.com (and any other domains you want to include) as "Denied" domains in the EMail -> EMail Configuration -> Receiving Email -> Anti-Relay Settings screen.
Under EMail -> EMail Configuration -> Receiving Email -> Permit and Deny Lists you can also confgure the system to reject mail based on the IP address or domain name.
Hope that helps.
Hi Phil Thanks for you response and highly appreciated on the time you a lot on this.
I have done through with the setup wizard but I don't know on what part should I place my IP Address of my INTERNAL MAIL Server.
Should I place the IP Address of my INTERNAL Server under DNS and ROUTING configuration or under Emai Configuration?
I also am interested in response to this.
I found here (Universal Network Solutions Inc.) how to install and set-up MEG.
Base on the link/guide above, they put the IP Address of the INTERNAL MAIL SERVER under Email Configuration > Sending Email