odoo16/addons/mass_mailing/data/mailing_list_data.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <data noupdate="1">
        <record id="mailing_list_data" model="mailing.list">
            <field name="name">Newsletter</field>
        </record>
        <record id="mass_mailing_contact_0" model="mailing.contact">
            <field name="name" model="res.users" eval="obj().env.ref('base.user_admin').name"/>
            <field name="email" model="res.users" eval="obj().env.ref('base.user_admin').email"/>
            <field name="list_ids" eval="[(6,0,[ref('mass_mailing.mailing_list_data')])]"/>
        </record>
    </data>
</odoo>