[Dovecot] Mailbox directory permissions (LDA, 0600 -> 0660, virtual users)

Hello,

I have a quite common dovecot configuration with virtual users support:

1. User configuration is stored in MySQL database.
2. Mailboxes are owned by vmail:vmail with permission 0600 or drwx------.

Is it possible to change mailbox mode to 0660?

Dovecot version is 2.1.7 Part of SQL configuration:

user_query =
SELECT
CONCAT_WS('/', home, u.uid, d.domain_name, u.user_name) AS home,
500 AS uid,
500 AS gid
FROM users u
LEFT JOIN domains d ON u.domain_id = d.id
WHERE
u.user_name = '%n' AND
d.domain_name = '%d' AND
u.active = 1

Regards.

-- M.