Funny, I’ve been struggling with this problem today for many many hours, before I bumped into this month old post: Monday-code python quickstart local dev - #5 by Matias.Monday
Tl;Dr - the Python code wouldn’t work locally with Monday. Not sure why they haven’t explicitly written it in the documentation.
If you’re looking to send an email, you may want to dive into the Python code (services\mail_service.py) - I suspect it doesn’t work either. If you do find a method for email sending from Monday code without using an external email service, I’d be happy to hear about it too.