MariaDB and DBMail: do not switch from mysql

[Sergej Pupykin <ml@xxxxxxxxxxxx>]

Hello,

it looks like mariadb has problems in "order by". Following query
returns data in wrong order:

SELECT
    l.part_key,
    l.part_depth,
    l.part_order,
    l.is_header,
    DATE_FORMAT(ph.internal_date,GET_FORMAT(DATETIME,'ISO')),
    data
FROM
    dbmail_mimeparts p
JOIN dbmail_partlists l ON p.id = l.part_id
JOIN dbmail_physmessage ph ON ph.id = l.physmessage_id
WHERE l.physmessage_id = <ID>
ORDER BY l.part_key,l.part_order ASC;

I've had headache with my mail server. Switching back to mysql helps.