I just tried to install & configure data mail pro over an existing free data mail installation. Dada mail discovers the existing configuration and I chose the upgrade option: Create a new .dada_config file.
I entered all database information correctly but the installation complains it cannot connect to my SQL Server. I tried deleting the original data mail database, created a new one with new user & password, but still getting the same error message.
Port is set to auto. There was no problem with the free version.