How to Configure Microsoft Graph OAuth 2.0 for Email SMTP

How to Configure Microsoft Graph OAuth 2.0 for Email SMTP

Microsoft Graph OAuth 2.0 SMTP Configuration Guide

Microsoft has deprecated basic SMTP authentication for most tenants. OAuth 2.0 via Microsoft Graph is now the recommended and more secure approach. This setup allows applications to send email without storing mailbox passwords.

Prerequisites:

Before you begin, ensure the following are available:

⚠️ Note: Application permissions require admin consent and cannot be approved by regular users.

Step 1: Register an Application in Microsoft Entra ID

Create App Registration

  • Log in to Microsoft Entra ID

  • Navigate to: Applications → App registrations → New registration

  • Fill in the form:

    • Name: Email OAuth

    • Supported account types: Single tenant

    • Redirect URI: Not required

  • Click Register

Capture App Identifiers

After registration, copy and securely store:

  • Directory (tenant) ID → TENANT_ID

  • Application (client) ID → CLIENT_ID

Step 2: Create a Client Secret

  • Open the registered application

  • Navigate to: Certificates & secrets → Client secrets

  • Click New client secret

  • Define:

    • Description (e.g. SMTP OAuth Secret)

    • Expiration period (recommended: 12 or 24 months)

  • Click Add

⚠️ Important: Copy the Value immediately. It will not be shown again.

  • Client Secret Value → CLIENT_SECRET

Step 3: Assign Microsoft Graph API Permissions

Add Permission

  • Go to API permissions

  • Click Add a permission

  • Select Microsoft Graph

  • Choose Application permissions

  • Search and select:

    • Mail.Send

  • Click Add permissions

  • On the API permissions page

  • Click Grant admin consent

  • Confirm the action

✅ Status should show Granted

Step 4: Configure SMTP Email Settings in the Platform

Once Microsoft-side configuration is complete:

  • Log in to the Web Application Admin Panel

  • Navigate to: Admin → Reseller Settings → SMTP Email Settings

  • Fill in the fields using:

    • Tenant ID

    • Client ID

    • Client Secret

    • Sender mailbox

Testing and Validation

After saving the SMTP settings:

  • Trigger a test email from the platform

  • Confirm:

    • Email is delivered successfully

    • No authentication errors appear

If email fails:

  • Reconfirm Mail.Send permission

  • Ensure admin consent was granted

  • Verify the sender mailbox exists and is licensed

Troubleshooting

Issue: Unauthorized or invalid client

  • Confirm Tenant ID and Client ID are correct

  • Ensure the secret value (not secret ID) is used

Issue: Insufficient privileges

  • Mail.Send permission not granted

  • Admin consent missing

Issue: Emails not received

  • Check spam/junk folder

  • Confirm sender address matches configured mailbox





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