Google oAuth2 error Bad credentials

[BogdanMoisa]

We have had a project for several years that sends emails through a gmail account using a TIdSMTP component.
For authentication, the setting IdSMTP1.AuthType := satDefault was made and as the password an application password set in the gmail account was used.
Now we are trying to do the same thing using oAuth2. I downloaded GMailAuthDemo, things work fine when obtaining a RefreshToken and then when obtaining an AccessToken.
Unfortunately we are unable to get past IdSMTP1.Authenticate. The error "UserName and Password not accepted ..." is returned.
The IdSMTP1.AuthType parameter is set with the value satSASL.
We tried setting the IdSMTP1.Password parameter with either the initial account password, the application password, or the AccessToken but the result is the same.
I ran the project on both Delphi 10.4.2 and Delphi 12.2 but the result is the same.

Can you help us with an idea?
Thanks

[geoffsmith82]

The username and password on IdSMTP1 should be blank. The app should not see the password at all - it is only entered in the web browser.

If you try and send a message, in the log screen have a look at the line that looks like

S:AUTH XOAUTH2 dXNlcj1ncHRzbdgsdfgpbC5jb20BYXV0aD....

Copy the first 20 or 30 characters (not all of it) after the S:AUTH XOAUTH2 and paste it into https://www.base64decode.org/ . Does the start of it contain your email address?

[BogdanMoisa]

Hi Geoffrey,

Thanks for your reply.

I reran the test setting, as you indicated, null values for the IDSMTP1.Password and IDSMTP1.UserName parameters.
What seems strange to me now is that the email sending now works correctly on one of our computers, but on my computer I get the same error message "UserName and Password not accepted ... ".
It is clear that there is a setting somewhere on my computer that leads to this behavior.
Can you suggest where I should look?

Thanks