I have a model inheriting mail.thread (for example helpdesk.ticket).

I'd like to modify the notification emails sent to partners if a message is created in this thread. Best would be if I could override the email template, but only for this model, meaning that just overriding "mail_template_data_notification_email_default" doesn't work. I would like to set a new template instead.

I tried setting the context['custom_layout'] of the partners notified by the mail, but I can't find the correct method to override to set this.

Any help is very much appreciated!