What does 'Authenticated user is not authorized to send mail' mean when using GSuite API?

Email marketer from Google Workspace Forum User explains that if using domain-wide delegation, the issue might be that the service account hasn't been granted the necessary permissions to impersonate the user and send mail on their behalf. This requires an administrator to configure domain-wide delegation correctly within the Google Admin console.

Email marketer from Reddit user explains that the error often arises from improper configuration of API permissions within the user's Google Workspace account. The user suggests navigating to the Google Cloud Console, selecting the appropriate project, and verifying that the 'Gmail API' is enabled and the necessary OAuth scopes are configured correctly.

Email marketer from Digital Ocean explains that OAuth 2.0 requires a user to grant specific permissions (scopes) to an application. The OAuth 2.0 guide suggests ensure that the correct 'https://mail.google.com/' scope is requested and that the user has granted access to this scope during the authorization flow.

Email marketer from Stack Overflow shared that if you are using a service account for sending emails on behalf of users, the issue can be that the service account is not granted impersonation rights. This means it can't act as the user and send emails. You need to grant the service account impersonation rights for the specified user.

Email marketer from Reddit suggests that the Google account used to authenticate may be suspended, even if temporarily. He suggests logging in via the web interface to ensure the account is active and not under any kind of restriction.

Email marketer from Stack Overflow User explains that this error typically indicates that the user account has been authenticated successfully, but the application lacks the necessary permissions to send email on behalf of the user. The user recommends checking the OAuth 2.0 scopes to ensure that the application has been granted the 'Send As' permission.

Email marketer from freeCodeCamp explains that if you're using a service account, ensure that the service account has been granted the appropriate domain-wide delegation permissions. This usually involves granting the service account access to impersonate the user on whose behalf the email is being sent.

Email marketer from StackExchange user explains you need to check that the Gmail API is turned on within the 'Enabled APIs' section of the Google Cloud console. Even with correct scopes, the API must be explicitly enabled for the project to function correctly.

Email marketer from Developer Community forum shares that the Gmail API has rate limits to prevent abuse. If you're sending too many emails in a short period of time, you may be temporarily blocked from sending email via the API, thus leading to the "unauthorized" error.

Email marketer from EmailDeliverabilityBlog.com shares that another less common, but possible, reason is the API requests using an older, non-compliant TLS version, which is not accepted by the mail server. Therefore, ensure that the latest TLS version (TLS 1.2 or greater) is used in your API requests.

Expert from Email Geeks explains that the authentication is broken and the smarthost is refusing permission to send, suggesting the user needs to open a ticket with their IT desk. Also says Google has shut off their ability to send mail.

Expert from Email Geeks mentions that if the API error message is accurate, the ability to send email via the GSuite API has been revoked, suggesting opening a support issue with Google and suggesting the user is likely using a spam service or has a wordpress plugin that is compromised. They have passed Google’s threshold for spamming.

Expert from Email Geeks explains that the user has logged in to the API successfully, but the user doesn’t have permission to send email. Suggests this isn’t email-related and needs someone who knows the service to diagnose it, like in a support issue.

Expert from Word to the Wise shares that a compromised or problematic user account could be the root of the problem. Even if the API key itself is correctly configured, problems with the specific Google account using the API can cause the 'unauthorized' error. An account audit to rule out such causes is recommended.

Expert from Email Geeks suggests the error is an API response indicating the authenticated user is not authorized to send mail through the API endpoint, possibly due to a misconfiguration or a 403 error code being more appropriate.

Expert from Email Geeks explains that in O365/Azure, users can exist without email access, preventing them from sending email. This can be similar in Google Workspace, where Gmail can be disabled for accounts.

Expert from Spam Resource explains that the issue could be related to API key restrictions and permissions. Ensure that the API key being used has the necessary permissions to send emails. Restrictions such as IP address or referrer restrictions could also prevent the API key from being authorized.

Documentation from Google confirms that the email address or domain may need to be verified within the Google Workspace settings. Unverified domains can cause issues with sending emails through the API. Therefore, ensure your domain/email is properly verified.

Documentation from Auth0 explains the Role-Based Access Control (RBAC) mechanism. It says RBAC is used to control access to application features based on the roles assigned to a user. The 'unauthorized' error could signify that the user's role does not permit them to send email through the API, requiring an administrator to update their role permissions.

Documentation from Google Workspace Admin Help explains that the error suggests the authenticated user lacks the necessary permissions to send mail through the API. This can stem from several issues, including incorrect scopes granted during authorization, the user's account lacking the 'Send As' permission for the mailbox, or organizational policies restricting API access.

Documentation from Microsoft Learn details the process of SMTP Authentication, emphasizing that for a user to send mail through an SMTP server, they must first authenticate their identity. This involves providing valid credentials that the server can verify against its user directory. If authentication fails or the user lacks permission, the server returns an 'unauthorized' error.