Man - you nailed it on the head. My ever so helpful DNS provider routed my MX record to their mail server. Changed it mine and everything is...
Sent another email. No output in the mail.log, mail.err, or syslog
Sent another message. No output in maill.log, mail.err, or syslog. Same 550 error on bounced email.
I followed the virtual domain setup on the forge @ http://www.howtoforge.com/virtual-users-domains-postfix-courier-mysql-squirrelmail-debian-lenny...
Separate names with a comma.