free email service much like gmail or hotmail

I would like to set up my own free email service much like gmail. My budget is $400.00. I do have my own server at hostgator. I would like the login box intergrated into my homepage template. I will be looking at all bids untill the end of this month and then I will pick a winner. People that have built them before and can show me links to their work will move to the front of the line. I will test every inch of the program before final payment is made. The email system needs to handle tons of free email accounts. This is not for a small company but rather for a web based email servive like gmail.