OK... answered at least my problem and perhaps yours.

Read this posting by Mike Horton:

"Administrative emails are sent as the email account assigned to the administrator account specified under Admin->Site Settings->Advanced Settings->Other Settings while test emails are sent from the email address specified under Host->Host Settings->Host Details. This way if I'm your host (gmss.org) but your site is different (chris.com) emails come from @chris.com instead of @gmss.org (causing your users confusion."

In my case, I am hosting with PowerDNN which requires a different SMTP server set up for the Host account as compared to the Admin account.

To perhaps offer better clarity, and hopefully Sebastian will correct me if I am wrong, I had the host’s SMTP server configured correctly using the Admin’s email account for authentication. This allowed email’s being sent from modules, such as the Feed Back module, to work correctly, as well as emails being sent to the administrator notifying of a new registration. However, emails notifying registrants of their registration status were not being sent for I had not properly configured the SMTP server towards the Host email account for authentication, which in my instance required a different configuration as compared to the Admin’s account.

I hope this helps Chris...

Roger