From: Scott on
Thanks for the reply.

"Isn't it a bit unusual to authenticate using a Windows domain account
and send using an external email address in the MAIL FROM command???""

Im not sure, was just the first method i tried (entered into this post), i
enabled and tested all authentication methods with no luck so simply setup
the following:

Exchange Managment Console
Server Configuration
Hub Transport
Click SERVER name
Add new Receive Connector
Called it RELAY
Add server IP
Port 587
"From IP addresses" enetered were for the internal LAN only. No direct net
based access to this server/service/port.
Autentication = TLS , Externally Secured
Permissions = Exchange Servers


In outlook select accounts
Select the pop3 account (change or double click)
Outgoing mail server IP entered
More Settings
Outgoing server tab
Uncheck SMTP requires authentication (cant get this working at the moment
but will be enabled in the future)
Advanced, change outgoing smtp from 25 to 587
Test Account, next , finish.

At least my users can send email using there POP3 account profile now.

Thanks for the reply.