Error "Invalid login: 535 5.7.139 Authentication Unsuccessful"

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Overview

This article explains that the following error occurs when the system attempts to send an email notification:

Error sending email: Invalid login: 535 5.7.139 Authentication unsuccessful, user is locked by your organization’s security defaults policy.

Applies To

  • Email Provider

Cause

The Microsoft Outlook Simple Mail Transfer Protocol (SMTP) provider directly returns the error. The provider likely rejects the request because the submitted credentials do not have the necessary permissions.

Solution

To resolve this issue, perform the following steps:

  1. Contact the Outlook SMTP provider administrator.
  2. Review documentation from Microsoft regarding this specific error.