social/fetchmail_thread_default/demo/data.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright 2017 Tecnativa - Jairo Llopis <jairo.llopis@tecnativa.com>
     License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl). -->

<odoo>

    <record id="demo_sink" model="mail.channel">
        <field name="name">mailsink</field>
        <field name="email_send" eval="True"/>
        <field name="description">Unbounded email sink</field>
        <field name="alias_contact">everyone</field>
        <field name="public">private</field>
        <field name="group_ids" eval="[(4, ref('base.group_user'))]"/>
    </record>

    <record id="demo_server" model="fetchmail.server">
        <field name="name">Demo server</field>
        <field name="type">pop</field>
        <field name="server">pop3.example.com</field>
        <field name="default_thread_id" eval="'mail.channel,%d' % ref('demo_sink')"/>
        <!-- <field name="default_thread_id">mail.channel,%(demo_sink)d</field> -->
    </record>

</odoo>