social/mass_mailing_partner/views/res_partner_view.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright 2015 Pedro M. Baeza <pedro.baeza@tecnativa.com>
     Copyright 2015-16 Antonio Espinosa <antonio.espinosa@tecnativa.com>
     Copyright 2015 Javier Iniesta <javieria@antiun.com>
     Copyright 2016 Antonio Espinosa - <antonio.espinosa@tecnativa.com>
     Copyright 2020 Tecnativa - Manuel Calero
     License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html). -->
<odoo>

    <record model="ir.ui.view" id="view_partner_form">
        <field name="name">Partner Form with mailing contacts</field>
        <field name="model">res.partner</field>
        <field name="inherit_id" ref="base.view_partner_form"/>
        <field name="groups_id" eval="[(4, ref('mass_mailing.group_mass_mailing_user'))]"/>
        <field name="arch" type="xml">
            <div name="button_box" position="inside">
                <button name="%(mass_mailing.action_view_mass_mailing_contacts)d"
                        context="{'search_default_partner_id': active_id,
                                  'default_partner_id': active_id}"
                        type="action"
                        class="oe_stat_button oe_inline"
                        icon="fa-envelope-o">
                    <field name="mass_mailing_contacts_count"
                           widget="statinfo"
                           string="Mailing contacts"/>
                </button>
                <button name="%(mass_mailing.mailing_trace_action)d"
                        context="{'search_default_partner_id': active_id,
                                  'default_partner_id': active_id}"
                        type="action"
                        class="oe_stat_button oe_inline"
                        icon="fa-envelope-o">
                    <field name="mass_mailing_stats_count"
                           widget="statinfo"
                           string="Mass mailing stats"/>
                </button>
            </div>
        </field>
    </record>

    <record id="view_res_partner_filter" model="ir.ui.view">
        <field name="name">Partner Search with mailing contacts</field>
        <field name="model">res.partner</field>
        <field name="inherit_id" ref="base.view_res_partner_filter"/>
        <field name="groups_id" eval="[(4, ref('mass_mailing.group_mass_mailing_user'))]"/>
        <field name="priority">20</field>
        <field name="arch" type="xml">
            <field name="category_id" position="after">
                <field name="mass_mailing_contact_ids" string="Mailing List"
                    filter_domain="[('mass_mailing_contact_ids.list_ids','ilike', self)]"/>
            </field>
        </field>
    </record>

</odoo>