Connection to mail service works fine, and the oauth setup worked perfectly. Where do I find the logs? I dont see anything relevant in ~/frappe-bench/logs/frappe.log or the schedule.log
For troubleshooting email, I usually look at the Error Log List in the UI, and in the Email Queue List, failed messages may have useful info. More info on logging can be found here: https://docs.frappe.io/framework/user/en/logging
There have been numerous threads here on 365 oauth , a search of the forum might turn something up. For example