Yeah, this would be good to have.

As internally, built-in email templates are handled very annoyingly, adding this will probably prompt a rewrite of that system. Just dumping my thoughts here for future reference:

• add a MailTemplate.role field, nullable, possible values: submission.new (the ack template), submission.new.internal, submission.accept, submission.reject, question.reminder, submission.draft.reminder (actually, this will be a regular custom template, I think, so you can use multiple/different ones), schedule.new
• Add a uniqueness constraint (event, role), so that each template can only exist once per event
• Migrate existing event template data, turn ack_template etc into properties
• Make sure forms, cloning etc still work
• Group templates into built-in and custom ones for less scrolling / easier finding of custom email templates
• Add get_builtin_placeholder method that returns extra allowed placeholders for built-in templates
• Make template selectable in draft reminder email form
• make sure the template can't be used in the regular sendmail form

All this stuff is now done, so it’s only a matter of a) building a template select into the draft proposal form, or b) creating a new template type, "draft proposal reminder".

Awesome!