There’s confusion about the OAuth2 scope required to send email via GMAIL.
There are two ways to programmatically send email using your GMail account:
- Connecting to smtp.gmail.com using the SMTP protocol (i.e. using Chilkat.MailMan)
- Calling the GMail REST API over HTTPS using Chilkat.Http or Chilkat.Rest.
The scope for IMAP, POP, and SMTP access is https://mail.google.com/
See https://developers.google.com/gmail/imap/xoauth2-protocol
If your app is not formally verified by Google (which, at the time of this writing, involves a yearly fee) then you’ll see an “unverified app” warning in the browser during the OAuth2 authorization flow.
With the HTTP REST API, more granular restricted scopes, such as https://www.googleapis.com/auth/gmail.send can be used.
Chilkat provides examples in all supported programming langauges for both SMTP and HTTP/REST on example-code.com.
For example: