Another day is about to go by before I can look into this adequately. After adding my G-suite email address and password, the error is the same. I there a way to get more information than that sending didn’t work? production.log says:
Started POST "/admin/email/test" for 999.99.99.99 at 2018-05-02 15:28:09 +0000
Processing by Admin::EmailController#test as */*
Parameters: {"email_address"=>"some@where.com"}
Sent mail to some@where.com (671.5ms)
Completed 422 Unprocessable Entity in 5068ms (Views: 2.8ms | ActiveRecord: 37.1ms)