social/mail_digest/data/config_param.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo noupdate="1">
  <record id="mail_digest_enabled_message_types" model="ir.config_parameter">
    <field name="key">mail_digest.enabled_message_types</field>
    <!-- enabled by default for each message type -->
    <field name="value">email,notification,comment</field>
  </record>
</odoo>