I'm having trouble authenticating through OAuth2 to Google's SMTP service.
I obtain an `access_token` using `SignedJwtAssertionCredentials`, passing a user and a certificate from a service account:
However, I get the error response:
It's basically "Username and Password not accepted" without much other information.
Google's examples assume that you have an "installed app" and thus a `client_secret` with which you obtain an authorization code through a web-based verification step – or that you've already got an `access_token`. Is there a limitation in Google's SMTP service that you can't use an authorization from a service account?
Here's the example code in Python that I have used as a reference:
Help much appreciated.
\malthe