GMail OAuth

We were using Collaborator 13.x and GMail's SMTP server to send notification emails. To do so, we had to allow "less secure" methods to connect to GMail. Recently, GMail has disabled this functionality and requires a higher security when connecting.

Our version of Collaborator did not have the option to use OAuth2.0. We upgraded to the latest (14.x). The description of the password field now mentions using the access token instead of the user's password. I have created several credentials via the Google cloud, but i cannot seem to get things working. Has anyone had luck? 

Using the gmail email address:

- I have created an OAuth credential and used the secret.

- I created a service account and used the key

Using service account:

- I use the key associated with the service account

i seem to get a "failed to connect" error. i'm using the same smtp.gmail.com url and port 587 that i was using before.

doing some online research, i might need a refresh token and/or access token. How do i obtain these things? Secondly, it seems the access token may expire. i do not want to update the token every hour, so i'm not sure that the access token is correct.