ir_actions_view.xml

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

        <record model="ir.ui.view" id="view_server_action_form_template">
            <field name="name">ir.actions.server.form</field>
            <field name="model">ir.actions.server</field>
            <field name="inherit_id" ref="base.view_server_action_form"/>
            <field name="arch" type="xml">
                <xpath expr="//page[@name='code']" position="after">
                    <page string="Email" autofocus="autofocus"
                            attrs="{'invisible': [('state', '!=', 'email')]}">
                        <p attrs="{'invisible': [('model_id', '!=', False)]}">
                            Please set the Base Model before setting the action details.
                        </p>
                        <group attrs="{'invisible': [('model_id', '=', False)]}">
                            <field name="template_id"
                                    on_change='on_change_template_id(template_id)'
                                    attrs="{'required': [('state', '=', 'email')]}"/>
                            <p colspan="2" attrs="{'invisible': [('template_id', '!=', False)]}">
                                Choose a template to display its values.
                            </p>
                            <p colspan="2" attrs="{'invisible': [('template_id', '=', False)]}">
                                The values displayed hereunder are informative. When sending the email, the values
                                will be taken from the email template.
                            </p>
                        </group>
                        <group attrs="{'invisible': ['|', ('model_id', '=', False), ('template_id', '=', False)]}">
                            <label for="email_from"/>
                            <div>
                                <field name="email_from" nolabel="1'" readonly="1"
                                        attrs="{'required': [('state', '=', 'email')]}"/>
                                <p attrs="{'invisible': [('email_from', '!=', False)]}">
                                    Your template does not defined any email_from. Please update your template.
                                </p>
                            </div>
                            <field name="email_to" readonly="1"/>
                            <field name="partner_to" readonly="1"/>
                            <field name="subject" readonly="1" attrs="{'required': [('state', '=', 'email')]}"/>
                            <field name="body_html" readonly="1" attrs="{'required': [('state', '=', 'email')]}"/>
                        </group>
                    </page>
                </xpath>
            </field>
        </record>

    </data>
</openerp>