Chilkat POP3 and SMTP not working with gmail scope "gmail.readonly" and "gmail.send"

Question

I'm writing a desktop email client, in C++, using chilkat library version 9.5.0.93. Gmail api scopes "gmail.readonly" and "gmail.send" are not sufficient to make POP3 or SMTP work. The app is working only when I request full access scope "mail.google.com".

However, Google rejects my verification request because they claim that gmail.send and gmail.readonly should be sufficient.

Chilkat Soft says on twitter, that SMTP can require full access scope, however according to them POP3 should work without full access. Chilkat Software

If you know some trick to make it work or maybe have some advice about Google verification, please let me know.

Scopes string: "openid email https://www.googleapis.com/auth/gmail.send https://www.googleapis.com/auth/gmail.readonly"

CkMailman::VerifyPopLogin ->

Chilkat log:

POP3 response indicates failure. AUTH_XOAUTH2_response: ***** --pop_xoauth2 POP3 authentication failed --Pop3Authenticate Authentication failed.

CkMailman::VerifySmtpLogin ->

Chilkat log:

... Failed to login using XOAUTH2 method --smtpAuthenticate ConnectionType: SSL/TLS --smtpAuthenticate --smtpConnectAndAuthenticate Failed.

When I change scopes to: "openid email https://mail.google.com/" everything starts to work

Answer 1

You should be able to reply to the message you got from the verification team.

Let them know that you are going though the smtp server and not the gmail api. They are correct that the Gmail api will allow for https://www.googleapis.com/auth/gmail.send scope. However the smtp server only allows for the https://mail.google.com/ scope.

You can forward them the link to the documentation where it clearly states

oauth_20_scopes