social/mass_mailing_partner/views/mail_mass_mailing_contact_view.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>
     Copyright 2016 Antonio Espinosa - <antonio.espinosa@tecnativa.com>
     License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html). -->
<odoo>

<record model="ir.ui.view" id="view_mail_mass_mailing_contact_tree">
    <field name="name">mail.mass_mailing.contact.tree.partner</field>
    <field name="model">mail.mass_mailing.contact</field>
    <field name="inherit_id" ref="mass_mailing.view_mail_mass_mailing_contact_tree"/>
    <field name="arch" type="xml">
        <field name="email" position="after">
            <field name="partner_id"/>
        </field>
        <field name="email" position="attributes">
            <attribute name="attrs">{'readonly': [('partner_id', '!=', False)]}</attribute>
        </field>
        <field name="name" position="attributes">
            <attribute name="attrs">{'readonly': [('partner_id', '!=', False)]}</attribute>
        </field>
    </field>
</record>

<record model="ir.ui.view" id="view_mail_mass_mailing_contact_search">
    <field name="name">Add partner search field and group by</field>
    <field name="model">mail.mass_mailing.contact</field>
    <field name="inherit_id" ref="mass_mailing.view_mail_mass_mailing_contact_search"/>
    <field name="arch" type="xml">
        <field name="email" position="after">
            <field name="partner_id"/>
        </field>
        <filter name="group_create_date" position="after">
            <filter string="Partner"
                    name="group_partner"
                    context="{'group_by': 'partner_id'}"/>
        </filter>
    </field>
</record>

</odoo>