'Access rules of mail.compose.message:
- create: if
- model, no res_id, I create a message in mass mail mode
- then: fall back on mail.message acces rules'

@api.multi
def check_access_rule(self, operation):

    if ((operation == 'create') and (self._uid != SUPERUSER_ID)):
        message_values = {}
        self._cr.execute(('SELECT    DISTINCT    id,    model,    res_id    FROM    "%s"    WHERE    id    =    ANY    (%%s)    AND    res_id    =    0' % self._table), (self.ids,))
        for (mid, rmod, rid) in self._cr.fetchall():
            message_values[mid] = {'model': rmod, 'res_id': rid}
        author_ids = [mid for (mid, message) in message_values.iteritems() if (message.get('model') and (not message.get('res_id')))]
        self = self.browse(list((set(self.ids) - set(author_ids))))
    return super(MailComposer, self).check_access_rule(operation)
