'Short-circuit parent method for mail groups, replace the default
footer with one appropriate for mailing-lists.'

@api.multi
def send_get_mail_body(self, partner=None):

    if ((self.model == 'mail.channel') and self.res_id):
        channel = self.env['mail.channel'].browse(self.res_id)
        base_url = self.env['ir.config_parameter'].get_param('web.base.url')
        vals = {'maillist': _('Mailing-List'), 'post_to': _('Post    to'), 'unsub': _('Unsubscribe'), 'mailto': ('mailto:%s@%s' % (channel.alias_name, channel.alias_domain)), 'group_url': ('%s/groups/%s' % (base_url, slug(channel))), 'unsub_url': ('%s/groups?unsubscribe' % (base_url,))}
        footer = ('_______________________________________________\n                                                                                                %(maillist)s:    %(group_url)s\n                                                                                                %(post_to)s:    %(mailto)s\n                                                                                                %(unsub)s:    %(unsub_url)s\n                                                                                ' % vals)
        body = tools.append_content_to_html(self.body, footer, container_tag='div')
        return body
    else:
        return super(MailMail, self).send_get_mail_body(partner=partner)
