social/mass_mailing_partner/wizard/partner_mail_list_wizard.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright 2015 Pedro M. Baeza <pedro.baeza@tecnativa.com>
     Copyright 2015 Antonio Espinosa <antonio.espinosa@tecnativa.com>
     Copyright 2015 Javier Iniesta <javieria@antiun.com>
     License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html). -->
<odoo>

<act_window name="Add to mailing list"
    res_model="partner.mail.list.wizard"
    src_model="res.partner"
    view_mode="form"
    target="new"
    key2="client_action_multi"
    id="action_partner_mail_list"/>

<record model="ir.ui.view" id="partner_mail_list_wizard_form">
    <field name="name">partner.mail.list.form</field>
    <field name="model">partner.mail.list.wizard</field>
    <field name="arch" type="xml">
        <form string="Create contact mailing list">
            <group>
                <field name="mail_list_id"/>
            </group>
            <footer>
                <button string="Add contacts to mailing list" name="add_to_mail_list"
                    type="object" class="oe_highlight"/>
                <button string="Cancel" class="oe_link" special="cancel" />
            </footer>
        </form>
    </field>
</record>

</odoo>