social/mass_mailing_custom_unsubscribe/models/mail_mass_mailing_list.py

# -*- coding: utf-8 -*-
# © 2016 Pedro M. Baeza <pedro.baeza@tecnativa.com>
# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).

from openerp import fields, models


class MailMassMailing(models.Model):
    _inherit = "mail.mass_mailing.list"

    not_cross_unsubscriptable = fields.Boolean(
        string="Don't show this list in the other unsubscriptions",
        help="If you mark this field, this list won't be shown when "
             "unsubscribing from other mailing list, in the section: "
             "'Is there any other mailing list you want to leave?'")