Email This Issue supports OAuth2 authorizations to access email services such as Gmail or Microsoft 365 (since version 8.1.1).
OAuth2 authorizations is inherently complex and takes up multiple configurations need by you.
Enable OAuth2 authorization in your service provider
Enable OAuth2 Authorization in your Google Account
Enable OAuth2 Authorization in your Microsoft o365 Account
Save OAuth2 Client Credentials received from your Service Provider in Email This Issue
Use the saved client credentials in SMTP Connections and Incoming Mail Accounts
Perform authorization to allow Email This Issue access the email service
Authorize Email This Issue to access Gmail accounts
Authorize Email This Issue to Access Microsoft 365 Accounts
These are the steps the app cannot perform by itself and needs configuration by an expert with administrative rights at the email service provider.