did you find a solution please !

Mohamed Zouine! Thanks for the above information furnished. I'm still a beginner and in need of detailed explanations.(tutorial sort of thing)

Hi, you should first create email templates for the request/approval/refection.

Then you create a function and add it to the create button and it should be like this :

template = self.env.ref('module_where_tepmlates_are_defined.your_template_id')
self.env['mail.template'].browse(template.id).send_mail(self.id)