mail_view.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <record model="ir.ui.view" id="inherit_fetchmail_cleanup">
        <!-- must be unique in this module. -->
        <field name="name">inherit_fetchmail_for cleanup</field>
        <field name="model">fetchmail.server</field>
        <!--parent python entity -->
        <field name="inherit_id" ref="mail_environment.inherit_fetchmail"/>
        <!-- modulename.view -->
        <field name="arch" type="xml">
            <field name="is_ssl" position="after">
                <field name="cleanup_days"/>
                <field name="purge_days"/>
            </field>
            <field name="password" position="after">
                <field name="cleanup_folder"/>
            </field>
        </field>
    </record>
</odoo>