Iphone

Migrating from Exchange 2003 to Exchange 2007 and we have external POP3S clients.

All Exchange 2007 Roles are running on the single new Exchange 2007 server.

Problem:
Exchange 2007 Default: Relaying for external authenticated users/computers is not permitted. (by using the pop3s basic authentication for SMTP)

They get the SMTP error "Server Response: '550 5.7.1 Unable to relay', Port: 25"

I cannot figure out figure out how to permit relay for authenticated computer/user.

(I am surprised at how diffiicult they have made Exchange 2007 to configure > mostly command line - - does anyone know why most of the configuration is no longer graphical ?)

Iphone

The GUI has been designed to be used for day to day work only - in an attempt to streamline the management console. For infrequently used items the command line is the primary interface. Remember that everything in Exchange 2007 is script-able.

You need to review the settings on the Receive Connectors under Hub Transport in Server configuration.
You should have two connectors, a default and a client connector.
Ensure that authentication is enabled, and that the permission groups have been set.