mysql> select
    ->   emails.endereco as user,
    ->   emails.password,
    ->   '/var/spool/mail/nonlocaluser@nonlocaldomain.com.br' as userdb_home,
    ->   'maildir:/var/spool/mail/nonlocaluser@nonlocaldomain.com.br' as userdb_mail,
    ->   8 as userdb_uid,
    ->   12 as userdb_gid,
    ->   concat('*:storage=', emails.quota) as userdb_quota_rule,
    ->   'Trash:storage=100M' as userdb_quota_rule2,
    ->   'Y' as proxy_maybe,
    ->   NULL as host
    ->   from emails
    ->   where emails.endereco = 'nonlocaluser@nonlocaldomain.com.br' and emails.ativa = 1
    -> union
    -> select
    ->   NULL as user,
    ->   NULL as password,
    ->   NULL as userdb_home,
    ->   NULL as userdb_mail,
    ->   NULL as userdb_uid,
    ->   NULL as userdb_gid,
    ->   NULL as userdb_quota_rule,
    ->   NULL as userdb_quota_rule2,
    ->   'Y' as proxy_maybe,
    ->   imapproxy.host as host
    ->   from imapproxy
    ->   where imapproxy.dominio = 'nonlocaldomain.com.br'\G
*************************** 1. row ***************************
              user: NULL
          password: NULL
       userdb_home: NULL
       userdb_mail: NULL
        userdb_uid: NULL
        userdb_gid: NULL
 userdb_quota_rule: NULL
userdb_quota_rule2: NULL
       proxy_maybe: Y
              host: 10.252.25.2
1 row in set (0.00 sec)

mysql>