431273 Roundcube Troubleshooting and mailserver IP Configuration

I need an experienced programmer with excellent skills in windows and linux servers to do the following work: 1. Setup OpenVPN 2.11 with toughest settings on a dedicated linux server running Centos. The openVPN will have to be integrated with my custom client Auth script which allows clients to authenticate to the server. I will provide the custom client Auth script. 2. Change my windows 2003 dedicated server mail IP. Currently the main IP of this server is blacklisted by Yahoo and hotmail and I need to change the IP to another IP on the server. However, the this main blacklisted IP is also used by the openVPN application running on this server and I would like to leave this IP intact for the openVPN application. Only the IP for receiving/sending emails will be changed. 3. Fix some errors in the Roundcube webmail installed on this windows dedicated server . The problem is that when sending emails, no confirmation of email sent are received and old emails/inbox emals cannot be deleted. I will provide the details of all the error messages.