Mailbox does not exist

New 10.4.4 Server install. Firing up the SMTP after creating all users in WGM and get this on a test email to user in the SMTP log file: Feb 11 21:39:41 main postfix/pipe[1259]: B27D43F162: to=<user@domain.com>, relay=cyrus, delay=1, status=bounced (data format error. Command output: user: Mailbox does not exist ) The user clearly exists in the OD and the email account shows as well under the Inspector. In the Mail section on Server Admin, under > maintenance > acconuts - there is only one registered user (my account) and no others. I'm not even sure how my account appeared - but that account accepts outside mail. Any clues on how to proceed? It's been 8 hours troubleshooting thus far. I'm about ready to chuck the system and drop in a wintel box (yes, I'm that angry.) TIA