Summary
The 'Authenticated user is not authorized to send mail' error when using the GSuite API signifies that the authenticated user or application, despite successful authentication, lacks the necessary permissions to send emails. This can stem from a multitude of reasons spanning incorrect configurations and policies to account specific problems. OAuth 2.0 scopes, disabled APIs, improper domain-wide delegation, user's account settings, account suspensions, non-compliant TLS versions, rate limiting, missing impersonation rights for service accounts, API key restrictions, and potentially a compromised user account are all possible root causes. Resolving this requires a multi-faceted approach, checking API configurations, account settings, and security measures.
Key findings
- Permissions: The authenticated user lacks sufficient permissions to send emails through the GSuite API.
- OAuth Scopes: Incorrectly configured or missing OAuth 2.0 scopes are a common cause.
- API Status: The Gmail API might not be enabled within the Google Cloud Console.
- Domain Delegation: Improper domain-wide delegation configuration for service accounts is often to blame.
- Account State: Suspended or restricted Google accounts can trigger this error.
- TLS Versioning: Use of outdated TLS versions (older than TLS 1.2) can lead to authorization failures.
- Rate Limiting: Exceeding Gmail API's rate limits might temporarily block sending capabilities.
- Impersonation Rights: Service accounts lacking impersonation rights for the intended user can cause authorization issues.
- API Key Restrictions: API key restrictions, like IP address or referrer restrictions, might be interfering.
- Compromised Accounts: Compromised or otherwise problematic user accounts could be the underlying issue.
- General Authentication: There may be a general authentication problem with your connection.
Key considerations
- Verify OAuth Scopes: Ensure that the appropriate OAuth 2.0 scopes (especially 'Send As') are requested and granted.
- Enable the API: Confirm that the Gmail API is activated within the Google Cloud Console for the project.
- Configure Domain-Wide Delegation: Properly set up domain-wide delegation in the Google Admin console if using service accounts.
- Check Account Status: Verify that the Google account is active and free from any restrictions by logging in through the web interface.
- Update TLS Version: Utilize TLS version 1.2 or higher in your API requests for improved security.
- Respect Rate Limits: Monitor your email sending volume to stay within the Gmail API's rate limits.
- Grant Impersonation: Grant service accounts the necessary impersonation rights for users on whose behalf emails are sent.
- Check API Key Setup: Inspect your API key setups and ensure your key has the correct IP permissions.
- Check Account for Problems: Perform a check of the account to ensure it has not been compromised in any way.
- Check with support: Sometimes its best to ask Google what the problem may be by opening a ticket with support.
What email marketers say
10 marketer opinions
The error 'Authenticated user is not authorized to send mail' when using the GSuite API typically indicates that the authenticated user or application lacks the necessary permissions to send emails. This can stem from a variety of factors, including incorrect OAuth 2.0 scopes, disabled APIs, improper domain-wide delegation, suspended accounts, TLS version incompatibility, rate limiting, or a lack of impersonation rights for service accounts. Addressing this issue requires careful review and configuration of permissions within the Google Cloud Console and Google Workspace settings.
Key opinions
- OAuth Scopes: Incorrect or missing OAuth 2.0 scopes, especially the 'Send As' permission, can prevent email sending.
- API Status: The Gmail API must be explicitly enabled within the Google Cloud Console for the project to function.
- Domain Delegation: Improperly configured domain-wide delegation can prevent service accounts from impersonating users.
- Account Status: Suspended or restricted Google accounts can trigger authorization errors.
- TLS Version: Outdated TLS versions may be incompatible with the mail server, causing authorization failures. TLS 1.2 or greater is recommended.
- Rate Limits: Exceeding Gmail API rate limits can temporarily block email sending.
- Impersonation Rights: If using a service account, ensure it has impersonation rights for the user on whose behalf the email is sent.
Key considerations
- Check OAuth Scopes: Verify that the necessary OAuth 2.0 scopes are requested and granted during the authorization flow.
- Enable APIs: Ensure the Gmail API is enabled in the Google Cloud Console for the project.
- Configure Domain-Wide Delegation: If using domain-wide delegation, configure it correctly in the Google Admin console.
- Verify Account Status: Log in to the Google account via the web interface to ensure it is active and unrestricted.
- Use Latest TLS: Ensure that the API requests use the latest TLS version (1.2 or greater).
- Respect Rate Limits: Monitor email sending volume to avoid exceeding Gmail API rate limits.
- Grant Impersonation Rights: If using a service account, grant it impersonation rights for the appropriate user.
Marketer view
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.
12 Sep 2021 - Google Workspace Forum
Marketer view
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.
28 Dec 2023 - Reddit
What the experts say
7 expert opinions
The 'Authenticated user is not authorized to send mail' error in GSuite API indicates that, while authentication is successful, the user lacks permission to send emails. This can result from broken authentication, a refusing smarthost, revoked API access (potentially due to spamming), API key restrictions, user account issues, misconfigurations, or disabled email access. Troubleshooting involves checking API keys, user accounts, and potentially opening a support ticket.
Key opinions
- API Permission: The authenticated user lacks permission to send email via the API.
- Broken Authentication: Authentication processes may be failing, preventing authorization.
- Smarthost Refusal: The smarthost might be denying permission to send emails.
- Revoked API Access: Google may have revoked API access, possibly due to spam-related violations.
- API Key Restrictions: API key settings, such as IP or referrer restrictions, may be preventing authorization.
- Account Problems: Issues with the user account itself (compromised or misconfigured) can lead to the error.
- Account Access: User may have an account without email access enabled.
Key considerations
- Check API Keys: Verify that API keys have the necessary permissions and are not restricted.
- Examine User Accounts: Audit user accounts for compromise, misconfiguration, or disabled email access.
- Review Smarthost Configuration: Check the configuration of the smarthost to ensure it's not blocking the user.
- Investigate Revocation: If API access is revoked, investigate potential spamming activity.
- Open Support Ticket: Contact Google support for assistance, particularly if the root cause remains unclear.
- Address Misconfigurations: Ensure all API configurations are correct as well as SMTP.
Expert view
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.
14 Feb 2022 - Email Geeks
Expert view
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.
16 Apr 2025 - Email Geeks
What the documentation says
4 technical articles
The 'Authenticated user is not authorized to send mail' error in GSuite API signifies a lack of necessary permissions for the authenticated user. This can be caused by incorrect authorization scopes, missing 'Send As' permission, restrictive organizational policies, authentication failures, and unverified domains. Addressing this issue involves ensuring correct scope configurations, proper SMTP authentication, role-based access control, and domain verification.
Key findings
- Incorrect Scopes: Insufficient OAuth scopes during authorization can prevent email sending via the API.
- Missing Permissions: The user's account may lack the 'Send As' permission for the mailbox.
- Organizational Policies: Organizational policies can restrict API access, leading to authorization failures.
- Authentication Failures: Failed SMTP authentication, or invalid user credentials can trigger unauthorized errors.
- Unverified Domains: Unverified email addresses or domains in Google Workspace settings can cause sending issues.
- Role Based Access Control: Role of the user does not permit them to send email through the API.
Key considerations
- Review OAuth Scopes: Ensure the application requests and the user grants the appropriate OAuth scopes.
- Verify Permissions: Confirm the user's account has the necessary 'Send As' permission for the mailbox.
- Check Organizational Policies: Investigate any organizational policies that might restrict API access.
- Validate Authentication: Ensure SMTP authentication is correctly configured and user credentials are valid.
- Verify Domain: Verify the email address and domain within Google Workspace settings.
- RBAC configurations: Ensure that the correct roles are set in Auth0 for the application.
Technical article
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.
1 Jun 2023 - Google Developers
Technical article
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.
6 Jun 2022 - Auth0
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