campanhas_email/views/res_config.xml

<?xml version="1.0" encoding="utf-8"?>
<openerp>
    <data>

        <record id="view_marketing_configuration_mass_mailing" model="ir.ui.view">
            <field name="name">marketing.config.settings.mass.mailing</field>
            <field name="model">marketing.config.settings</field>
            <field name="inherit_id" ref="marketing.view_marketing_configuration"/>
            <field name="arch" type="xml">
                <xpath expr="//div[@name='module_mass_mailing']" position="after">
                    <div>
                        <field name="group_mass_mailing_campaign" class="oe_inline"/>
                        <label for="group_mass_mailing_campaign"/>
                    </div>
                </xpath>
            </field>
        </record>

    </data>
</openerp>