моя ошибка
у меня выборка из двух таблиц идёт, когда переписывал запрос, не учёл
тогда
query = SELECT substring(login from 1 for 1)||'/'||login||'/Maildir/' from mailusers where login = '%u'||'@'||'%d';

authlib
SELECT login as username,'' as cryptpw,               \
                        pass as clearpw,506 as uid,                           \
                        506 as gid,'/mailboxes/'||substring(login from 1 for 1)||'/'||login as home,\
                        '' as maildir,                                  \
                        30 as quota,fullname,                    \
                        'disableimap' as options              \
                        where login = '$(local_part)'||'@'||'$(domain)';
Если опять не ошибаюсь