Username and Password are not accepted. Message from smtp server: 535-5.7.8 Username and Password not accepted. For more information, go to
535 5.7.8 https://support.google.com/mail/?p=BadCredentials 46e09a7af769-71fc998e5bdsm465137a34.51 - gsmtp
It appears you can not use Gmail with user/pass way and oauth we do not support yet, we’ve got in plans add the ability to connect an email account with oauth but at this moment there is no any ETA.
If they support it it should work, the server just uses the configuration you provided.
I can recommend you to use on the email services from the following list: