Hey @gigir ,
If you don‘t mind to spend some bucks you would get a great experience regarding your topic with our app Kindly.
You could easily set up your reminder plan to schedule reminders for open draft orders after 7 days from the invoice being sent. That‘s basic procedure.
What‘s maybe even more interesting to you is our latley published option to send SMS reminders with what we see a much higher conversion rate compared to email.
Finally, also not unimportant, to improve your reminders effectivness you can check your email performance in the analytics page.
Let me know what you think!
cheers,
raphael