Ahhhh, well after a few days of troubleshooting I have FINALLY found the problem!!!
When I copied/pasted from Falko's excellent tutorial
I must have made an error when inserting as I inserted:
smtpd_recipient_restriction = permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination
and misspelled smtpd_recipient_restrictions leaving out the "S" as indicated above. I changed it to the following and everything worked as expected:
smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination
The tutorials with excellent, however, I got hit with a violent case of "PEBKAC" !!!
Funny thing is, no errors were presented stating an incorrect setting. I ran:
which also reported nothing.