We need to achieve the following, creating a email server to receive and forward mails.
1) That way our client can send the mail to our server (with our brand) and our server will forward the message to sms@XXXXX.com,
2) The subject must stay intact.
3) We will need the reverse to work as well, similar procedure we will need to send the message to our client automatically when we receive replies from sms@XXXXX.com
It's a VOIP SMS service, that converts incoming SMS messages to emails, and once you reply to the email, it will send out the SMS. But because we are reselling the service, we need to mask the domain name to be branded with our own.
Here's an article on this topic. http://superuser.com/questions/50941/how-can-i-automatically-forward-an-e-mail-and-change-sender
Ideally I'd like to modify my own server, and achieve this.