SMTP Transparent Proxy

Communications between an Exchange 2007 Edge Transport server and the Internal Network in an Exchange Server 2007 organization over SMTP port 25, are encrypted by default. It uses TLS (Transport Layer Security) method, defined in RFC 2246, as the protocol for establishing a secure connection between a client and a server. TLS (Transport Layer Security) is capable of authenticating both the client and the server and creating an encrypted connection between the two.

The process of establishing a transparent proxy is explained below,

In SMTP Administrator Click on Server Settings

Description For Proxy Connection :

Source IP: Here we add the IP of the source sender (i.e. in Exchange 2007, it will be the IP of Hub Transport Server )

Destination IP: Here we add the IP of the destination where all the outgoing mails will be delivered (i.e. In Exchange 2007, it will be the IP of Edge Transport Server)

Port: The Port is that of Edge Transport which should be 26, since while installing MailScan for Exchange on Edge Transport, it will automatically change Edge Transport Server port from 25 to Port 26.

After adding appropriate IP's and Port, click on ADD button then click on SAVE button.