from markupsafe import Markup from odoo import api, models class MailComposeMessage(models.TransientModel): _inherit = "mail.compose.message" @api.onchange("template_id") def _onchange_template_id_wrapper(self): super()._onchange_template_id_wrapper() context = self._context if "is_quoted_reply" in context.keys() and context["is_quoted_reply"]: self.body += Markup(context["quote_body"]) return