social/mass_mailing_sending_queue/data/ir_config_parameter.xml

<?xml version="1.0" encoding="utf-8"?>
<!-- Copyright 2016 Antonio Espinosa <antonio.espinosa@tecnativa.com>
     License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl). -->

<openerp>
<data noupdate="1">

<record id="sending_batch_size" model="ir.config_parameter" forcecreate="True">
    <field name="key">mail.mass_mailing.sending.batch_size</field>
    <field name="value">500</field>
    <field name="group_ids" eval="[(6, False, [ref('base.group_system')])]" />
</record>

</data>
</openerp>