By default exchange 2010 is securely configured to only allow sending through an application like outlook. In some instances workstations running programs need to be able to send using SMTP on port 25.
In order to allow this on exchange 2010 in exchange management console under server configuration go to the Hub transport. Add a new receive connector from the menu on the right
Set the execute the end to a suitable name. Configure this name in the DNS on the active directory controller and as the outbound SMTP server in the application on the workstations
Configure the local IP address on the server that the relay connector will listen on. This will be the IP address configured in your DNS server. Set the range of IP addresses that are allowed to transmit to this relay. Generally you will want to exclude the external Routers internal address to prevent possible relaying from the Internet.
Set authentication to transport layer Security
And permission groups to anonymous users
Telnet to relay.domain.local 25 and confirm a correct response
Now you will be able to send from the workstations on the local area network