Google / Gmail { “error”: “invalid_grant”

Hi @alexanderkoch096 ,

Thanks for reaching out, and I am so sorry to hear about the trouble.

As your API & Services status is published already, the OAuth token in Gmail will reset for any event breaking the connection, including but not limited to:

1. Changing Google password
2. Enabling or disabling 2FA
3. Google account access reset
4. Activation of Google advanced protection program
5. Revocation of the app to profile
6. App OAuth permission revoked by Google
7. App moved from public mode to private/internal mode by Google (or by a user whose user domain is not in the allowed org domain zone)
8. App verification failure on reaudit
9. Suspension of Google account
10. User requested linked account unlinking
11. The user does not use the app for 6 months (automatically expires refresh token)
12. The user adds/removes sensitive or needs review scopes to the app but does not complete the app review process
13. If the user is at the maximum limit for OAuth tokens to a Google profile (50) or for the service (25 for example in analytics), activation of a new refresh key will also automatically revoke the earliest key

Once you can make sure that none of these from the above list is happening, the last step is to head over to the WP Mail SMTP > Settings page, and click on the “Remove Connection” button. Then click on the “Allow plugin to send emails using your Google account” button to re-enable access.

Hope this helps. Thanks 🙂