If you had already added an account in Automatic Email Manager using Office365, you have now to change from basic authentication (with your email login and password) to modern authentication (identification given by your O365 account).
It is easy, please read these steps:
1. Edit your account in Automatic Email Manager
2. Move to the server settings
3. Click on ‘We recommend you use Modern authentication’
4. Click on ‘Test connection’, it will open the Microsoft Office365 modern login to ask you to enable Automatic Email Manager to check your emails, valid, it is finished.
IMPORTANT: To be able to send emails with Office365 and OAUTH you have to enable the option in your Microsoft admin panel like describe here :