Configures the system-level Azure AD application credentials that allow the platform to access Office 365 / Outlook mailboxes on behalf of users (for the inbox integration feature).

###### Registering an App in Azure Active Directory

1. Open the Azure Portal — App registrations.
2. Click New registration.
3. Set the redirect URI to: `https://<your-domain>/app/office365Callback`
4. After creation, copy the Application (client) ID and the Directory (tenant) ID.
5. Go to Certificates & secrets → New client secret and copy the value.
6. Under API permissions, add Microsoft Graph delegated permission: `Mail.Read` (and `Mail.Send` if composing is needed). Grant admin consent.

###### Settings

Client ID
  The Application (client) ID from Azure AD.
Client Secret
  The client secret value. Stored encrypted at rest.
Tenant ID
  The Azure AD directory (tenant) ID. Use `common` to support multiple tenants, or enter a specific tenant ID.
Redirect Domain
  The domain used in the redirect URI registered in Azure (e.g. `app.example.com`).

Open Azure App Registrations