social/mail_bcc/views/views.xml

<?xml version="1.0" encoding="UTF-8"?>
<odoo>
  <data>
    <record id="mail_bcc_form" model="ir.ui.view">
        <field name="name">mail.template.mail_bcc</field>
        <field name="model">mail.template</field>
        <field name="inherit_id" ref="mail.email_template_form"/>
        <field name="arch" type="xml">
            <xpath expr="/form/sheet/notebook/page[2]/group/field[@name='email_cc']" position="after">
                <field name="email_bcc"/>
            </xpath>            
        </field>
    </record>
  </data>
</odoo>