Register the Application in Microsoft Entra ID

1. Go to Entra portal → App registrations → New registration

2. Select Create Your Own Application

   Name the app (e.g., FastClose Email Sender)
   Click Create
   

   

   
   

3. Choose Supported account types: Single tenant
   Redirect URI: Not required
   Click Register

4. Under Enterprise Applications
   Select the newly created Application and Click Single Sign On
   Click Go To Application
   Select the Overview tab

Copy:

• Directory (tenant) ID

• Application (client) ID

• Click Endpoints and Copy the OpenID Connect metadata document (aka The OIDC well-known endpoint)

These will be used by your service to request OAuth tokens.

Create a Client Secret

1. In your app → Certificates & secrets

2. Click New client secret

3. Set an expiration period (recommended 1 year)

4. Copy the VALUE immediately — you cannot retrieve it later

You now have:

• Tenant ID

• Application Client ID

• Client Secret

• OIDC well-known endpoint

Assign API Permissions (Application Permissions)

You need Mail.Send (Application) — NOT delegated.

1. App → API permissions

   

2. Add a permission → Microsoft Graph → Application permissions

3. Add Mail.Send

   

   Click Grant admin consent