• Go to https://portal.azure.com
• Sign in with your Microsoft 365 admin account

• Navigate to App registrations
• Select App registrations from the left menu
• Click '+New registration'.
• Fill out:
  • Name: SMTP Email Sender App
  • Supported account types: Accounts in this organizational directory only (Single tenant)
  • Redirect URI: Leave blank
• Click 'Register'

After registration, note:

• Aplication (client) ID → Client ID
• Directory (tenant) ID → Tenant ID

• In your app registration screen, click on “Add Certificate & secret”.
• Click “+New client secret”.

• Provide a description (e.g. SMTP Auth Secret).
• Set an expiry (6 months, 12 months or 24 months)
• Click “Add”

Copy the value immediately - it is your Client Secret. You cannot view it later.

• Go to API permissions in the app.
• Click “+Add a permission”.

• Select “APIs my organization uses”.
• Search for and select “Microsoft Graph”.
• Choose “Application permissions”.
• Expand Mail and check “Mail.Send”.
• Click “Add permissions”.
• Click “Grant admin consent” to approve.

• Tenant ID: Found in Azure AD → Directory ID.
• Client ID: Found in Azure AD → Application ID
• Client Secret: Copied from Certificates & Secrets
• SMTP Scope: Mail.Send for Microsoft Graph.