Send Email - SMTP Config : Authentication Unsuccessful

Questions
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1

Describe the problem/error/question

Hello all,

Thank you for replying to my question. I have browsed to see if the community has encountered the same issue, it seems yes but the solution provided has not worked for me.

I have done a workflow, the end node, is a a send mail which takes in an email text and some attachments. For this workflow, i have used outlook but i was encountering much issue with grouping all attachments in one email with outlook node so i switched to send mail. Here i needed to setup the SMTP, which is the following :

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What is the error message (if any)?

Invalid login: 535 5.7.139 Authentication unsuccessful, user is locked by your organization’s security defaults policy. Contact your administrator. [FR4P281CA0231.DEUP281.PROD.OUTLOOK.COM 2026-01-05T09:01:22.690Z 08DE48C20541FBB5]

Please share your workflow

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(Select the nodes on your canvas and use the keyboard shortcuts CMD+C/CTRL+C and CMD+V/CTRL+V to copy and paste the workflow.)

Share the output returned by the last node

Invalid login: 535 5.7.139 Authentication unsuccessful, user is locked by your organization’s security defaults policy. Contact your administrator. [FR2P281CA0098.DEUP281.PROD.OUTLOOK.COM 2026-01-05T08:46:18.534Z 08DE4905AD2FFB67]

Information on your n8n setup

  • n8n version: 2.1.4
  • Database (default: SQLite):
  • n8n EXECUTIONS_PROCESS setting (default: own, main):
  • Running n8n via (Docker, npm, n8n cloud, desktop app): cloud
  • Operating system: windows
2

Hi @Sitingbull

As per the error states, your user account has been locked due to some organization policies. You’ll need to speak to your company IT Admin to unlock your user and possibly relax the policy rules for this user.

3

  1. Check Security Defaults:

    • Go to the Microsoft Entra admin center (Entra ID > Overview > Properties).

    • Select Manage security defaults and set it to Disabled, then Save (this is for service accounts/legacy apps).

  2. Review Conditional Access Policies: Check for policies that might be blocking legacy authentication or requiring MFA for the user/application.

  3. Enable SMTP AUTH: Ensure SMTP Authentication is enabled for the user account in the Exchange Admin Center if it’s needed.

  4. Use App Passwords: If MFA must remain on, users can generate an App Password from their security info page in their Microsoft account for apps that don’t support modern authentication.

check: Configure Security Defaults for Microsoft Entra ID - Microsoft Entra | Microsoft Learn