Send--receive email using web application

We want to integrate Gmail or Yahoo! Mail in a web application to send and receive emails. The features we need are: 1. User will authorize his/her Gmail account 2. User will go to the mail interface and select any email address from a list. This list will be populated from a MySQL DB or may be hard-coded. User cannot write the receiver email address anywhere. 3. Once the user sends mail to an email address 'xyz@[login to view URL]' the copy of the email should also come in the SEND folder of his Gmail. 4. As the recipient replies, the user should be able to open it in the Inbox of the web application. A copy of the same should also be there in the Gmail Inbox. 5. Till the time the authorization is active for the Gmail account, any mail send to the user from xyz@[login to view URL], a copy should also go to the Inbox of the application. The same process should take place with Yahoo! as well. We need prototype; we will integrate the prototype in our actual application. Please apply if you have created similar application before.