Yes, the table has data in it. I have examined it and it looks correct. Thanks for trying.
Could you answer one question? Does it look like the Dovecot service is involved in delivery to the mailbox? Here is an entry in the log:
Jan 29 15:56:06 mail postfix/pipe: 4AD4C57805F: to=<firstname.lastname@example.org>, relay=dovecot, delay=0.03, delays=0.01/0.01/0/0.02, dsn=2.0.0, status=sent (delivered via dovecot service)
Should I look there for the problem? I've been assuming Postfix is controlling 100% of the delivery.