I want to chime in here as well. I’m facing the same problem.
I am getting the 403 error when authorizing.
I can confirm the app is published and set to Production and the User type is set to External.
I also have another website I run that is working just fine with WPSMTP.
I have tried starting from scratch on a couple computers and made sure that I was not logged into any other gmail accounts and I was in a private window.
I was wondering if you could tell us specific questions we should ask our hosting provider about this?
I appreciate anyone’s help! Thank you very much!
