postfix/pickup[15883]: F34B965841CF: uid=1000 from=<webmaster>
postfix/cleanup[15907]: F34B965841CF: message-id=20160519164815.F34B965841CF@mysite.com>
postfix/qmgr[15884]: F34B965841CF: from=<webmaster@mysite.com>, size=398, nrcpt=1 (queue active)
dovecot: auth-worker(15911): Warning: mysql: Query failed, retrying: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '@example.org.' at line 1
dovecot: auth-worker(15911): Error: sql(john@example.org): Password query failed: You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '@example.org.' at line 1
dovecot: lda: Error: user john@example.org: Auth USER lookup failed
dovecot: lda: Fatal: Internal error occurred. Refer to server log for more information.
postfix/pipe[15909]: F34B965841CF: to=<john@example.org>, relay=dovecot, delay=0.02, delays=0.01/0/0/0.02, dsn=4.3.0, status=deferred (temporary failure)

postmap -q example.org mysql:/etc/postfix/mysql-virtual-mailbox-domains.cf

user = mailuser
password = <pw>
hosts = mailserver
query = SELECT 1 FROM virtual_domains WHERE name='%s'

user = mailuser
password = <pw>
hosts = mailserver
query = SELECT destination FROM virtual_aliases WHERE source='%s'