How to Fix WP Mail SMTP Pro Office 365 Authentication Errors
Question details
The user needs to resolve the MailboxNotEnabledForRESTAPI error encountered when using WP Mail SMTP Pro with Microsoft 365.
- Product
- Microsoft 365
- Device & OS
- not provided
- Scenario
- Connecting WordPress to an Office 365 mailbox using the WP Mail SMTP Pro plugin to send emails.
- Observed behavior
- The system throws a MailboxNotEnabledForRESTAPI authentication error, preventing the WordPress site from sending emails via Microsoft 365.
Ensure you have global administrator access to your Microsoft 365 account and admin access to your WordPress dashboard to verify mailbox settings and plugin configurations.
Verify Mailbox Status and Update SMTP Configuration
Check your Microsoft 365 admin center to ensure the mailbox is active, and update your WP Mail SMTP settings if using an on-premises setup.
The MailboxNotEnabledForRESTAPI error usually occurs when the integrated Microsoft 365 mailbox is inactive, soft-deleted, or hosted on an on-premises Exchange server instead of the cloud.
Log in to the Microsoft 365 Admin Center, navigate to Active Users, and confirm that the connected mailbox is active and possesses a valid license.
If your mailbox is hosted on-premises rather than in the cloud, navigate to the WP Mail SMTP Pro settings in WordPress and switch the mailer to 'Other SMTP' using your on-premises Exchange SMTP details.
In the WP Mail SMTP plugin settings, double-check that the Application ID, password, and authentication tokens exactly match those generated in your Microsoft Azure portal.
If the issue persists, attempt to authenticate using a different active Microsoft 365 mailbox to determine if the issue is isolated to a specific user account.
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Frequently Asked Questions
What does the MailboxNotEnabledForRESTAPI error mean?
This error typically means the Microsoft 365 mailbox you are trying to connect via WP Mail SMTP Pro is either inactive, soft-deleted, or hosted on an on-premises Exchange server rather than in the cloud.
Can I use an on-premises Exchange server with WP Mail SMTP Pro?
Yes, but you cannot use the default Microsoft 365 API mailer option. You must select the 'Other SMTP' option in the plugin and enter your on-premises Exchange server's specific SMTP settings.
How do I fix authentication token errors in WP Mail SMTP?
You can resolve token errors by removing the existing connection in the plugin settings, generating a new client secret in your Microsoft Azure portal, and re-authenticating the connection within your WordPress dashboard.
