In the following we will demonstrate how it really works in a company.
<1> Server collect Email Account from ISP mail at regular time interval or on demand.
<2> All Emails are first forwarded to speified internal Email account(s) for internal mail forwarding manually.
<3> Internal Email will be forwarded inside the Network.
<4> Internal mail services inide Network are handled by mail server inside the network.
<5> Outgoing Emails are first sent to internal mail server and then sent to external email server to send out.