Hi,

Create a server action on the stock.picking model (Delivery Orders)

Trigger: On Validation (when the delivery is marked “Done”)

Action: Execute Python Code → send email with attachments.

for picking in records:

    if picking.picking_type_id.code == 'outgoing' and picking.state == 'done':

        # Get customer

        partner = picking.partner_id

        # Generate Delivery Slip PDF

        delivery_pdf = env['ir.actions.report']._render_qweb_pdf('stock.report_deliveryslip', picking.id)[0]

        # Get related invoices

        invoices = picking.sale_id.invoice_ids.filtered(lambda inv: inv.state == 'posted')

        attachments = []

        # Attach Delivery Slip

        attachments.append(('Delivery_Slip.pdf', delivery_pdf))

        for inv in invoices:

            # Invoice PDF

            inv_pdf = env['ir.actions.report']._render_qweb_pdf('account.report_invoice', inv.id)[0]

            attachments.append((f'Invoice_{inv.name}.pdf', inv_pdf))

            # Invoice Excel (custom report needed)

            inv_xlsx = env['ir.actions.report']._render_qweb_xlsx('your_module.report_invoice_xlsx', inv.id)[0]

            attachments.append((f'Invoice_{inv.name}.xlsx', inv_xlsx))

        # Send email

        mail = env['mail.mail'].create({

            'subject': f"Delivery and Invoice for {picking.name}",

            'body_html': f"<p>Dear {partner.name},<br/>Please find attached your delivery note and invoice.</p>",

            'email_to': partner.email,

            'attachment_ids': [

                (0, 0, {'name': fname, 'datas': base64.b64encode(data), 'res_model': 'mail.mail'})

                for fname, data in attachments

            ]

        })

        mail.send()

Hope it helps.